It has been a month since I installed two of these T9's in a home with split systems. One controls a gas furnace with a/c and the other a heat pump. The gas furnace configuration wiring was easy. I initially wired the heat pump wrong but the thermostat warned me and it was a careful yet easy correction. By the way, it is my understanding if you have a heat pump with gas backup you need a T10 instead of a T9. It was easy to install a few remote sensors, and nice to be able to observe temperatures in those rooms/areas and (optionally) involve them in the calculation to run the system (the Priority feature). We are also liking the Geofence feature, an alternative to setting time based schedules, that (usually successfully) runs the system based on whether anyone (i.e. their phone) is home. Often the app is slow to report the local weather. At another location we have a Trane XL824. Overall the Honeywell is a little easier to use (both the thermoset and the app) but the Trane is probably a little more consistent when it comes to maintaining connectivity.
I love the easy access to adjust my thermostat. The only issue i had was the installation of the first thermostat it would not come on after some searches online and speaking to my brother in law I determined the fuse had blown. The installation of the 2nd one upstairs was flawless and worked to perfection.