Regarding Radio Thermostat products, I have come to agree with Jay. I can't recommend them. Unfortunately, I can't point to a solid alternative, either, at least not based on first-hand experience.
Summary of my (rather sad) experience over the last 10-12 years with thermostats:
Insteon I installed several variants of Venstar thermostat with Insteon module in two different houses. Thermostat generally worked ok, although comms were never very reliable. Bogus sensor data was sent and (apparently) bogus commands were occasionally received that caused the unit to jump to absurd setpoints at times. My last remaining Insteon unit's reliability went from bad to worse a year ago and I finally had to replace it.
Nest. Nice hardware, somewhat expensive. Uses Wi-Fi for comms. Connects you to the Google/Nest cloud (for better or worse) and (to some degree) ties you into their universe, including their concept of home/away. Initially these were well-supported via Indigo plugin called Nest Home, however now there are many limitations and incompatibilities using the device with Indigo. Basic setpoint setting and sensor tracking still work well. Functionality beyond that ("eco" settings, home/away assist, etc. ) are generally not supported properly.
Z-Wave CT100 Plus. Nice feature set, at least on paper. Reports humidity. Reasonable price. They are not trying to embed a "smart" hub inside the thermostat (in contrast to Nest) and did entail any dependence on outside cloud services (also in contrast to Nest). Unfortunately, the comms started out working well and (at least for one of my two devices) now seems to not be working reliably/correctly.
I don't relish the idea of having to purchase a new thermostat (yet again). For my next thermostat, I'll go with something that has solid recommendations from others in this forum and ideally is from a company with solid background in HVAC. Since Z-wave continues to evolve fairly rapidly, it is tempting to look at newer models (i.e., models that are at least Z-Wave Plus). In my opinion, the selection of Z-wave thermostats on the market is extremely limited - there are a handful of them available, many of them old (> 5yr) models, most made in China and sold by companies I've never dealt with before (RemoteTec, GoControl) and/or rebranded. Exceptions are Trane (I think made by RCS?) and Honeywell. Honeywell Lyric T6 (model TH6320WF2003/U) looks like an interesting candidate - anyone have experience with it?
I've established initial contact with Radio Thermostat about my problems with CT100-plus. I'll report back if I get a breakthrough there such as establishing I just had a bad unit or (hopefully) getting firmware updated to address the unreliable comms issues that I'm seeing.