JD - sorry for the delay, we're still in the moving process so it's slow going...
Ok, so previously, we had Vivint with its alarm.com integration. Door open close sensors, wireless motion, HD camera, smoke and carbon sensors, and the Kwikset 910 with alarm.com managing the user codes.
After adding the ST hub, it took me awhile to figure out how to successfully add the 2Gig as the secondary controller, and have it see the Kwikset 910. ST can see the lock and from the app or the SmartTiles dashboard. I can unlock and lock using ST remotely as well as having ST perform actions based on the lock status. So if the lock is unlocked, turn on the light if it's dark, etc.
Now, I have moved and am using the 2Gig standalone without Vivint and without alarm.com integration.
I have the same setup now with the 2Gig still managing the user codes. 2Gig and the ST hub can see the 910, and both of the Linear FS20Z relays I'm using as momentary switches to open and close our garage doors.
Some limitations however... ST can't see the user codes entered in the 910, just the unlocked / locked state. The alarm.com integration could perform actions based on the user code, such as text me when my children unlock the door but not my wife, or disarm the alarm when the lock was unlocked.
I haven't gotten any Iris devices yet, so I can't tell you how that all works.
You're probably right on with the security restrictions in ZWave, I know that previously, ST couldn't see the smoke / carbon, motion sensor. I also didn't see the door contacts, but I assume that was because the contacts were wired and wired up to the two hardwire zones on the 2Gig.
Let me know what else I can tell you, I think the next thing I want is the 2Gig doorbell.