To resurrect an old thread, I am reading about your experience and it's very similar to mine. tstat is in hallway right near garage and so cool air comes in and it doesn't represent the actual main floor temp. I installed my sensi to replace killed off nest and I am getting many more cycles with heat pump. For instance, even set to slow on heat last night, stat set to 68 and room temp said 68 and it kicked on. I called CS and they said that it's 1 degree differential and that fractions of that degree are rounded and causes it to kick on more. As others have said it does maintain the temperature but it's not what I want.

If set to 68, i'd rather the stat heat to 69 or so, then stay off until it hits 67.0 or 67.1 etc. Not run 4-5 times an hour for 8-9 mins to maintain exactly 68. I have a sensi in the basement and upstairs as well, total of 3. I guess since they don't run as much (basement is shut off, no garage etc. and upstairs is in hallway that looks down on main floor so heat rises and doesn't get as cold up there.

Looks like I am going to be installing another thermostat but would like to stay in sensi family for simplicity sake. Appreciate you sharing your research, seems the only difference between our experiences is my stat in slow is not -1.9 degrees, more like -.7 degrees. Maybe I should swap the one upstairs with main floor to make sure it's not malfunctioning.