Last week I was browsing Lowes website and found TH8320ZW for $20. I got one right way (price is now back to $160).
Installation and pairing was as easy as it could be, around 15 minutes.
Everything appears to be working fine. When I set the temperature using the sliders (ST app), the thermostat responds near real time.
I had it set on cool mode and hold on 74 degrees. From time to time I look at the app and it will tell me the temperature is set hold on 85 degrees instead (it switches automagically). At first I though it was a glitch on the UI so I went back to the thermostat it was actually showing 85.
This is bad because it means the AC will only turn on if the house temperature goes over 85.