I bought this one using the MassSave program. I then bought some 24V transformers to plug them in as I don't have a C wire. I kept my old ones in case I want to switch back. My total cost was about $50 for 3 thermostats to get them running.I’ve been using this one for the last few years. Works great. I don’t have a C-wire so I have to run batteries
My old ones were the 5+2 programmable, but clicking through all the buttons to change the program meant I rarely did. The setup on the Sensi app is very easy and flexible. The wi-fi control is the big winner, though, since it allows me to change the heat as needed. I find I use less heat since I can simply turn it off if I won't be home or will be home late. It provides decent reports about usage so you can see if one particular zone is running a lot.
I don't have cooling, so I'm not worried about them shutting that off. They do have the voluntary program on cooling where the utility can increase the temperature on high use days. I think they can up it to 78, but you have to have cooling and you have to sign up for that.
Overall, it was a great deal for me as it allowed me to get some extra features at a very low cost.