Brand new to Hubitat and don't even have the hub yet, but wanted to check. I know I need a Lutron bridge pro to integrate with this (and need it anyway for the Caseta system), but I was going to buy a Gen 3 Smartthings hub to use with motion sensors to activate the Lutron switches, but after doing some reading I'm not so sure I actually need the hub.
Can you confirm that this is indeed the case? The Hubitat hub can control ST devices like motion sensors and whatnot?
Thanks much!
Yes it can. No, you don't "Need" The ST Hub. I have motion sensors and their door sensors, as well as their moisture sensors. All work brilliantly with HE.
Scott
Almost any Z-Wave or Zigbee device (like all generations of SmartThings motion sensors) that can pair to ST can pair to Hubitat. These can only be paired to one hub at a time, so if you value the features that Hubitat provides (like local execution and the more-featured and also local Caséta integration), I'd go with Hubitat.
You don't really "control" a motion sensor--just pair it (and technically send configuration to it) and then more or less just receive events from it that you can do with as you please, compared to how you might really control, say, a switch or bulb--but it sounds like you have the right idea. Sometimes the ST hub is nice to have for firmware updates, but I'm not aware of any for the motion sensor, at least ones that have mattered for something (the only example I can think of here is the first batch or few of the 2018 SmartThings Buttons where the original firmware was prone to sending duplicate events). Otherwise, you'll find lots of people here who switched from ST to Hubitat and a few people who do use both for various reasons--but I wouldn't recommend starting that way.
Good luck!
Thanks guys! Appreciate the answers. So tell me this... if I don't have the actual smartthings hub, would I not be able to use the Smartthings app? Wasn't sure if Hubitat somehow still replicates the 'presence' of the hub even to the actual Samsung app. (sorry if i'm using the wrong terminology, i don't quite know the intricacies of how it all works, but i'm super willing to learn!)
You wouldn't really be able to use the ST app. It's more or less intended for setup and administration of an ST hub and monitoring and control of devices (and automations--SmartApps, in their terms) you have set up on that hub. (I say "more or less" because there might be some cloud-based things you can do without a hub, but this isn't how most people use it.)
Hubitat hub administration is done via a web-based UI hosted locally from the hub. If you've ever configured most routers, network printers, or similar devices from one, the idea is the same. For day-to-day monitoring and control (a function the ST app combines with administration, perhaps not well given the existence of things like the ActionTiles dashboard), you'll probably want to use something like Hubitat Dashboard rather than the straight-up admin UI, though it could work for that too. Hubitat Dashboard is a built-in app (Hubitat's term for automations, though this is a bit different from most apps), not to be confused with the mobile app. But speaking of that, the Hubitat mobile app makes accessing dashboards easy (and provides a way to get notifications and use presence), but you don't need it for anything (e.g., unlike ST, you do not use it for hub administration/setup). The dashboards are just webpages you can access via LAN or cloud URLs you can get from the admin UI.
( @bertabcd1234 I have two SmartThings accounts, one created years ago when I got their Hub and one I created in the last 6 months.. no hub, no hub required for creation of the account. It was tricky though. I started in the App and then had to finish in the IDE. After that it would work in the App too.
I can run cloud automations only. Kind of obvious, without a hub, no devices can be manipulated. Virtual devices, since they are cloud based, work fine. I did all of this because it came up in a HubConnect query and it made me curious. I didn't end up using it at all, but ti's there. 
)
You definitely need to keep your ST box. Makes a great coffee cup holder on your desk. 
The ONLY reason you might retain (and invariably not enough to buy) a SmartThings hub is if there is some integration available on that platform that is not available on HE. Usually this would be some specific cloud integration. Once configured you don't need the actual hardware. I have kept my ST Hub and yes, it is for a very specific and limited reason. HE as a local hub has the advantage of being local - not having to go out to the Internet to control or be updated with the status changes from your devices.
Is there something available on ST you can't implement on HE - aside from using the ST app (and just to complicate things there are two ST apps BTW) ?
IF you really wish to use the ST app for control then YES you would need a ST hub , at least initially to configure the devices and install the synchronisation with HE. But I think that is a very bad initial approach to engaging the power of the HE hub and a compromise to your control. It's imposing restrictions and complications from the start.
Wow, first off, this community is amazing!! Thank you sooo much for the intricate answers. You guys have definitely sold me 
I think I have most things sorted... I'm going to hold off on buying a ST hub, and have a Lutron Pro Bridge on the way.
One thing I am curious about that was mentioned by a few - cloud integrations - the ST hub might be needed. Forgive me, but what exactly is a 'cloud integration' that doesn't require talking to a local device?
I'm sure this is child's play when it comes to smart home automation, but to begin with I simply want to take a cheap motion sensor and have it turn on the bathroom light at 30% if it senses motion say between 9pm and 7am. That's where I wasn't sure if I needed the actual ST hub to talk to the Lutron switch.
"Cloud Integration" is anything that requires an Internet connection to get a result. Want to have Alexia turn on lights? The part where your recorded voice goes out to Amazon to be decoded requires a 'cloud integration.' You 'sign up for' the integration feature and then you can put keys or codes into an App or Driver to permit it to work.
Want weather info? You sign up for a specific service and get a Key as a result. Enter that key into a weather driver and you will get a bunch of weather data that you can use.
Hubitat supports many. So does SmartThings. Each do some better than the other. Therefore, some people stillprefer to maintain a ST account for that integration.
If you don't have any already: good. 
(Unless you like putting the Internet in the middle of things that shouldn't really need the Internet. Yes, my opinion--but also why many of us are here as opposed to some other platforms in the first place.)
A specific example is Ring. Samsung has an official partnership with them that allows integration with at least their doorbells (you can get button presses) and...at least formerly some sort of video on those and the cameras, possibly still now, but I'm not sure because I've never found a use for that in home automation. Nest is another (unless Google changed their mind about them, too...another thing I don't like: you're at someone else's mercy ). There are a few others. Hubitat doesn't not support cloud integrations; Samsung just happens to be a bigger name with more klout and a slightly longer history and has a few more, or at least a different set.
Hubitat has an Alexa skill, Google Home support, an IFTTT channel, Ecobee support, a Life360 app, and more, as an example of cloud services you can use natively. There are many more community offerings. Hubitat also offers its own cloud services, e.g., a way to use Hubitat Dashboard over the Internet for away-from-home control (some reviews of Hubitat often claim it's local-only; this isn't true, but the cloud components are optional).
Related: if you're looking for, say, a smart plug (or almost any device), Z-Wave and Zigbee devices that connect directly to the hub are your best bet. That cheap Wemo or Kasa or whatever WiFi plug may work, maybe with a cloud connection, maybe locally, but usually with a lot less ease than something that is officially compatible. (There's also in-between space: LAN integrations. Hubitat has several of these too, like Lutron and Sonos. The Hue Bridge integration is another. These work well, too.)
Ahh thanks so much! That really clarifies things alot. So much to learn. Is there a thread (I briefly looked but I missed it) where a list of commonly working sensors/buttons/etc... are listed with compatibility or prices/links?
These are a good place to start:
https://docs.hubitat.com/index.php?title=List_of_Compatible_Devices
and
Excellent! Thank you so much!!
Download the Hubitat app
