What home thermostat do you have?

2 x Ecobee 3 here...I can see the savings on my electric bill. Well worth the investment. The entire house up and down are at a constant temp.

Yep...
Oh, and it sounds like you’re covered here already, but make sure to check the C wire requirements of what you get.

Yeah, I've only ever heard of 2 problems with Ecobee. The first, people who try to install it themselves and don't know what they're doing. I got my tech straight from Ecobee and he said this was usually their issue. The second, is people thinking that there's a little oval piece of peel away plastic on the face of the thermostat itself. That's actually a room sensor, he said you'd be surprised how many people sit there and scrape it away despite it resisting being peeled.