I've wanted to try out Hubitat for a while, but (unfortunately?) I've been too content w/how SmartThings has been working for me. I know this may be hard to believe, but for me ST has been reliable and fast for quite some time now.
The majority of my core SmartThings automations are related to motion/lights and buttons. Using Iris and SmartThings motion sensors and local processing via the SmartThings Smart Lighting app, my response times are very fast (usually ~1s) and have been very reliable. I've also easily integrated Ring products into some automations (e.g., turning on all my front yard Ring camera lighting when I open my front door to take the the dogs out for a pee before bed).
For more complex if-then actions and Google Home announcements I use a combination of WebCore and Greg Hesp's Google Home Relay. Those have also been very reliable and prompt, and I can do just about anything I want with them.
Internet outages are rare enough at home that I can't remember the last time it happened, so any cloud processing I am using is very stable/reliable, and I have a solid home network (Ubiquiti EdgeRouter/NanoHD) that is fast and stable for ST hub connectivity.
So I'm still kind of wondering "Why Hubitat?" I may still try it just for fun, but I'd kind of like to have some additional "this part will be better" reasons to go through the pain of excluding devices from ST/adding to Hubitat/rebuilding automations, and additional complexity of running both Hubitat and ST hubs in my smarthome system (doesn't look like HE is ready to be my only hub yet). I know that I can "cheat" and share devices between the hubs, but that's not really giving HE the chance to do its stuff, and I want to know/confirm that it just works on its own.
I should note that going from a second or so for response times for motion/buttons to faster than that is not really enough to get me terribly excited.
So what are the main reasons (aside from the fun of new toys) to try HE when everything already "just works" on ST? I've listed a summary of my stuff below. Appreciate any suggestions on if/where I'm going to see the best bang for the buck/work converting to HE, and general comments on why you did it that may apply to me.
I've got:
ST motion and leak sensors
Iris motion sensors
Visonic contact sensors
Generic Zwave contact sensors
GE plugs
Zooz plugs
GE Zwave & Zwave+ dimmers/switches
Honeywell Zwave+ dimmers/switches
Fortrezz water valve
Schlage Connect BE469 lock (using Rboy's apps)
Ring doorbell and cameras
ST buttons (new version), Hue add-on switch, and other buttons
Some of your devices (Schlage locks, Fortrezz water valve) likely depend on custom DTHs. What are your plans to continue using these once ST ends developer access to the IDE to build custom DTHs (and apps). That isn't coming till sometime in 2021, but if I were in your position, I'd have a migration plan in place.
P.S. Welcome to Hubitat - even if it is just to explore your options ....
@danabw if your smart things works and hour happy I wouldn't bother changing. You'll likely get nothing more over smart things. We all want automation that works and I always have a eye on Smart things but I hear lots about cloud issues and outages so it's actually nice to hear someone who doesn't have issues. 1000% stay with what you have
I also am a ST user, and just bought the C7 to start working on the transition. While i also didn't have a ton of issues/errors with ST, they seemed to always happened at a time with noted WAF complaining.
The other reason i made the adjustment is my opinion regarding the old saying, nothing is free. Also, i'm not really sure what their business plan is for SmartThings, as Amazon, Google, others are taking away share. Samsung will need to adjust to a pay-for model at some point, unless they are happy to just have access to see/use our data, which i guess is also what Google Home/Amazon Echo are doing with my smart home network. Not sure what the eventual evolution is, but if the shift goes over to wifi, the traditional smarthub usage may be more diminished.
I'm technical, but nowhere near as some of the code gurus here. I have some reservations on the move in stepping up the effort on my side on the move to Habitat, however this community seems as well versed and helpful as the smartthings community.
I'll add one other thing without editing my original post. My SmartHome is getting more complicated, with a growing number of devices. I'm always hesitant that if my ST system bricks, i'd have to rebuild it all from scratch.
Not to mention WebCoRE and doesn’t Ring integration depend on a custom app/driver?
I switched from SmartThings due to the way custom drivers and apps had to function through the cloud as well as SmartThings cloud outages. Every time the SmartThings cloud went down, my wife became more displeased with my HA hobby. Even though the Hubitat has had some issues at times for me, they weren’t problems I couldn’t eventually figure out, and were mostly related to badly behaved devices. I also really like the fact that I’m not dependent on a cloud service to let me know if there is a fire, water leak, etc. It may be better than it was, but I’m not willing to deal with
Then you have your reason for switching already. With the new hub protection service you would never have that worry. Even without it, as long as you maintain a database backup, you would only have to rejoin zigbee devices and they would fall back into your rules. Z-wave would be more work though.
This was my biggest reason for switching to Hubitat. I moved two years ago and I moved my whole ST system from one house to another. It was a pain getting all my devices removed, re-paired and setting up all my rules again. This of coarse was unavoidable in a move, but it got me thinking, what happens when my hub dies.
The switch from ST to HE was fairly painless but still a bit of a hassle. It was made easier by the fact I could move things at my own pace no need to rush anything. Also Hubconnect, it's a great app that let me keep a few things on ST that have no integration in HE. I could move a few devices at a time and still control everything with HE.
Still unable to back up the device list, but that is coming as well it sounds like with the new Hub.
My reason for approaching a switch to Hubitat is I like to have automations run locally. Although by nifty workarounds I have managed that with SmartThings, it's very limiting. With Hubitat I can have more complex automations and they will still run locally.
I am just moving from ST to Hubitat myself and I am waiting for my hub to be delivered today. I have never noticed an outage with ST or had any issues to note. My main reason for moving to Hubitat was the changes coming to ST. Everything I have is in WebCore which hasn't seen an update now since last October. Knowing it will be going away and possibly replaced with another method made me decide to just do the switch now to Hubitat. I like the fact that it will be local too but that wasn't really a main decision factor for me.
Because of the local processing - incorporating a hubitat into your home is more like installing an air conditioner then say adding Netflix. As long as you have electricity and your hardware is functioning you will always have those devices available. Doesn't matter what the state of the company is, your internet connection, if there is a newer more popular protocol etc etc - everything should just continue to function as long as you want in the current state it is or until it dies. To me that's the real appeal - I am not tied to the cloud or a company.
I successfully continued to run my Hubitat hub during Hurricane Florence, for days while on generator. All of my local automations worked perfectly until we ran out of gas! Of course, we had no internet connection for a week, but at least my lighting still worked as designed. For a little while there, we were worried we might have to flip a switch by hand!
If you're happy with how your ST is running, by all means it's perfectly valid to stay there. I started on ST, and ran into limitations and reliability problems, so switched to Hubitat. I've been very happy with how it turned out. Much much faster response times, and a better developer platform for me to work it to my wishes.
That said, you titled this as "Trying to justify this to myself". LOL. Usually when I get to that point with my hobbies, the battle is already lost. Ima gonna do it, and I'm just looking for the defensible reason to tell to my wife!
The support for AlertMe / Iris V1 pairing brought me here, combined with the local processing and the ability to develop drivers for unsupported kit. The cloud service was my number one problem with the old AlertMe system, very slow and twitchy when updating rules on the original hub.
My biggest problem with Hubitat has been building a stable mesh, but that's because I've been using Xiaomi kit which is problematic (and not officially supported). So really, not a Hubitat issue at all.
If you haven't already, you'll find many HE users also run Node-RED (including myself) for a variety of reasons. I've never had any other hub myself but many posters in this community say that HE makes a far better hub than the others to incorporate Node-RED.
EDIT: I should also add that there are NR specific topics in this community where many post their flows for others to employ or use as an example. Search and ye shall find.
I'm not really bringing anything new to the table here, but I can tell you what I think my reasons for switching were.
1, Classic vs New. Was there ever anything more confusing than Samsung's apps?
Local execution. In this day and age, it seems like every place you have data on the Internet is going to be targeted, and eventually compromised. Having my rules, device names, etc, restricted to my home network is very appealing to my, and in my case, I don't use voice control, IFTTT, or really, any cloud based home automation connected services. In a word, really, Privacy.
Speed. Local automation speed has an effect on more than just motion lighting rules. Everything is affected by cloud latency & weird vendor issues with SmartThings and other cloud tied hubs. Perhaps automaton reliability and performance should be what you consider with regards to local execution.
Rule Machine -- while others rave about Node-Red, and I think it's fantastic that we're able to use Node Red, RM4 is pretty amazing itself. A bit hard to wrap your head around sometimes, but damn it's great.
This community. I have been on the internet for Decades (literally), and I have never seen a community as friendly or helpful as this one. Tips and advice are freely given, apps are built (at the drop of a hat), and it only takes the reading of a few threads that show interaction between developers, users and staff to realize how amazing this community is. Hubitat is worth it, almost for that alone.
Finally, I now (with a C7) have 3 hubs, all of which can do the job of automating my home. Redundancy for relatively low cost.
Until Hubitat, I never really considered a "community" as being part of any product. But the added value everyone on this forum brings to the table is real.
For the most part I agree with @Shaneb If your happy, I'm not going to be the one to convenience you to change, be happy. When that changes we'll be here.
Of course, we had no internet connection for a week, but at least my lighting still worked as designed. For a little while there, we were worried we might have to flip a switch by hand! 
