Follow up to say these A2 speakers have been fantastic.
The other day they stopped working. Called them and an actual human answered, in Texas. He seemed to think the amp had blown, but we decided to try a new power brick first. They had one out in a few days and voila! Problem solved, and they never asked for a dime. Really impressive.
Have used all of the above. The C4 unit was nice but dating looking (read ugly). The Nest was great but has become a pain. The Ecobee has been the best, not least of which is the remote sensor ability which nobody else has?