When I first started with Home Automation about 2 years ago, I did a little research on the advantages and disadvantages of Zigbee vs Z-Wave. I learned that Zigbee operates on the same frequency as 2.4 GHz wi-ft, thus there was the possibility of interference. Then there was the issue of the radio's range: Zigbee's range is considerably shorter than Z-wave. So based on the issue or interference and range, I decided to primarily us Z-wave.
However, I found out later that my Z-wave motion sensors were slow to turn on the lights. I researched this and the consensus is that zigbee motion sensors are generally faster to communicate than z-wave motion sensors. I replaced some of my z-wave motion sensors with zigbee, and indeed the zigbees respond faster.
Later, I found out that if one needs to unpair and pair a z-wave device, the rule "breaks." So you have to re-do your rules to get them working again. But with zigbee this is not the case. Apparently, zigbee devices have a hard-coded id. So if you unpair and then re-pair your device, the rule is not broken.
At this point, going forward I plan to primarily utilize zigbee devices. However, I would like input from the Hubitat community. Am I going in the right direction? Is there anything I'm missing? Is there some disadvantage of zigbee, or advantage of z-wave that I'm not considering?
This is "true" in most cases but is not absolute. There are several Z-Wave motion sensors that are "just as fast" as Zigbee sensors. However they are not as common or require adjustment of the settings form their defaults. Examples are the Zooz ZSE02, Dome Motion Sensor, previous Zooz ZSE09, Fibaro Motion Sensor after adjusting. The sensors do exist but Z-Wave sensors are generally made for "security" not "occupancy" so they are responding just not sending the "ON" to the gateway to react until either multiple motions or motion over a set time period. I'm sure other Z-Wave users have their favorites @bcopeland I'm sure has some.
This is correct currently with Hubitat.
Most Z-Wave gateways provide a "replace" function where you can replace a failed device with another of the exact same type. This means exact so it must be the same make/model etc. If this function existed with Hubitat this rule breaking would not be an issue, however it does not today. Something to keep in mind as the feature may be added in the future. Keep in mind if in the future you for whatever reason decide to try or use a different gateway there's not many that have good Zigbee support.
I think you've summarized it well, though I might add:
Z-Wave isn't the same frequency worldwide (only an issue if you plan on moving to another country or buying devices overseas--the controller and device have to match frequency)
In my experience, Z-Wave devices are a bit more "portable," meaning that pretty much any Z-Wave device will work to at least some extent with any Z-Wave controller/hub. For Zigbee, I've only found Hubitat and SmartThings to work well with a variety of arbitrary devices (Home Assistant has gotten better since the last time I tried it a couple years ago for this, but it wasn't great then; Vera still has a narrow whitelist of devices that doesn't appear to have changed since then). This was my experience when searching for an alternative to ST until Hubitat came along (yay Hubitat!).
My interpretation of the specs is that certified Z-Wave controllers need a Z-Wave "replace" function, which would more or less do what you're asking if replacing a failed node with a new device (it's not really intended for the same device replacing itself, and 700 Z-Wave requires device resets to send a notification to the hub which might un-pair them--not sure what the spec requires there--but it might at least help in some cases regardless). Hubitat is not certified, but if they are aiming for this, I expect they will at some point, otherwise third-party tools can already do this for you. You are correct that Zigbee devices can be remembered by their factory-set MAC (though resetting some devices may still disrupt some automations, like a Zigbee group in Groups and Scenes--just go in and click "Done" again to re-add the group ID to the bulb).
However, there's no reason to choose Z-Wave or Zigbee. I'd say most people run a mix of both. I know I do. Some devices are easier to find in one protocol vs. another (reasonably featured in-wall switches and dimmers are heavily favored for Z-Wave right now and probably will be until Inovelli comes out with the Zigbee line they've hinted at), and sometimes one has a more appealing price point. As long as you have good meshes for both, it's not a problem--that's actually one of the nice things about a hub like Hubitat, that it can tie them all together regardless of protocol.
I prefer Zigbee over Z-Wave, personally. For my needs, Zigbee has been more reliable and performs better. Currently, the only Z-wave devices I have are the repeaters that are part of my Iris 3210-L outlets.
Everything else is either Lutron Caseta, Zigbee, or DIY LAN devices (I.e. HubDuino).
It would be nice if Hubitat would add a Z-Wave replace feature. It is nice that Zigbee devices can easily pop back into their proper device if they are re-paired for any reason. I would like if they’d add a Zigbee replace option as well.
I think you summed it up well, but one thing that was avoided is that the possibility of interference with zigbee is much higher. Z-wave does boast very little interference, but the protocol is a bit more picky than zigbee. If there are a lot of radio networks running in your proximity, you're destined to run in to problems with zigbee. I feel like after I've researched both networks myself I will still use both and not lean to one as a go to. I have more Z-wave powered mains than I do zigbee, but there is also that little issue of there not being a standard for zigbee. This makes the devices more affordable, but you never know if what you get, for example xiaomi/aquara/mija will actually work reliably without issue. Z-wave being a certified protocol gives higher confidence that your device will be compatible with your hub.
Since hubitat doesn't "make" things work like other platforms have catered to brands, it's advisable to take great care with what your purchase for use. This still won't tip me in the direction of either protocol as I feel like they both have pros and cons as long as you understand how the protocol works and communicates.
For some people, I'm sure that ends up being true. However, FWIW where I live it's pretty congested with neighboring Wifi networks and I don't have any issues that I would attribute to zigbee device interference (due to wifi, or any other source).
Hmmmm.... I am not exactly sure what you mean. Zigbee has standards (ZLL, ZHA, 3.0, etc...) and has a certification process as well. Certified Products Search | IOT - CSA-IOT
Xiaomi devices do not claim to be Zigbee certified, as far as I know. They are designed to operate mostly in accordance with the ZHA1.2 specification, but they are not 100% complaint. This is what causes problems with these devices when used with any hub other than the Xiaomi hub. I have never used these devices as the cost savings has never been enough to outweigh the constant frustration they have brought to so many users.
I have run as many as 5 Zigbee networks and multiple WiFi access points in my home with zero interference issues. I know plenty of folks have brought this up as an issue, but it has never been a problem for me. Maybe I am just lucky.
Z-wave seems to be the source of many users’ issues, especially when mixing old and new Z-wave/Z-wavePlus devices together. My GE Z-wave switches and dimmers always gave me headaches on both SmartThings and Hubitat...thus the move to Lutron Clear Connect as my in-wall switches, dimmers, fan controllers, and Pico button controllers protocol. Zero issues with Lutron.
Same here. I have one zigbee network on channel 15 and other on channel 20, and thus far, no major issues.
No personal experience with this, but I have read a few times that 900 MHz equipment like old cordless phones and baby monitors can interfere with z-wave in North America.
Negative impacts to the hub that I've noticed recently - Flaky/bad Zwave devices cause slowdowns to the point of rebooting, Flaky/bad Zigbee devices can bring the Zigbee network offline as well as potentially dropping devices.
There are so many benefits/detriments with one compared to the other that I think the choice should be dictated more by your particular needs than anything else. Establishing a good mesh is important, which means that, unless you have lots of devices, whatever you get should be in one protocol, rather than mixing zigbee and z-wave.
I ended up with z-wave because I was focused on smart switches, and that market is dominated by z-wave.
Quoted directly from silabs
"With ZigBee the use of repeaters can be unreliable, especially since there are so
many different implementations of the protocol that compatibility can be hit or miss"
This is what I meant by that. Nothing more. I probably should have been more specific in my mention.
I guess that's one important caveat if you go with zigbee. You have to be picky about what manufacturers' products you use, as standards compliance varies wildly.
This is true with both protocols. You do have to be picky. But is one better than the other? That's the question. In my research, zigbee is gaining in popularity significantly, but because the number of devices you can have on a network is virtually unlimited. But, don't you have a limited number of child devices? If you want to get technical, where do you begin? I'd welcome using both protocols in my environment, but I consider myself to have a general understanding of both protocols and can acknowledge the challenges and benefits of each. And appreciate what might be necessary to get certain devices to work properly within my environment.
It's been said before that every environment has different challenges. This lies significantly and painfully true. There is no right answer to this question because of that.
Once again, I can only speak for my own setup of course , but I don't have a ton of devices and I still enjoy using both z-wave and zigbee (depending on what's available for a particular use case).
I do have devices that act as repeaters for each protocol, though.
This is where HE shines in terms of a Home Automation Hub I think. It's "flexibility" to handle most of the common devices and due to customization allow for expansion beyond it's basic parameters. So very nice.
Some have dedicated hubs for both Zigbee and ZWave so that is a possibility as well - giving you the "reliability" of single device type hub while allowing you the freedom to use whatever device you want.
Bear in mind also that Zigbee has a choice of channels whereas Z-Wave is fixed frequency (country allocated). If you do have interference problems on your local Z-Wave frequency that you can't eradicate, then you're pretty much hosed.
Also.. If you do run two or more Z-Wave controllers they will be on the same frequency and contend with each other for bandwidth and interference. You can potentially run multiple Zigbee controllers without these issues (but potential overlaps with WiFi)
Factually they operate on the same frequency and so contend for use of that. Obviously only if 2+ devices want airtime access at the same time. Not saying there will be problems, just there is potentially a performance impact which maybe insignificant (or not). Power usage reporting from sockets uses a lot of bandwidth for example. Low bandwidth (infrequent update) devices would not impact multiple controllers at all really.
. I am not exactly sure what you mean. Zigbee has standards (ZLL, ZHA, 3.0, etc...) and has a certification process as well. 
, but I don't have a ton of devices and I still enjoy using both z-wave and zigbee (depending on what's available for a particular use case).
