Pulled the trigger on this on BlackFriday. I was able to get two for a littlet over $100 after utility rebates. Both are running fine on the existing two* wire thermostat cable, but too soon to tell how beneficial they will be. At least now if we forget to turn down the heat at night we can do it from the warmth of our bed.

I had pulled new wire (which was a pain, and now i need to replace some baseboard wood) for the downstairs thermostat, expecting it to need a C-wire, but it doesn't.