And FWIW, the Ecobee Smart Sensors don't respond quickly enough for most automations. A more appropriate term might be "Occupancy Sensor." It can take quite some time (sometimes maybe a minute or so?) for motion to trigger the sensor as active. My guess is that the thermostat is only polling (or the sensors only wake-up and report) every minute or so in order to maximize battery life. The motion sensor in the actual thermostat seems to report almost instantly, though.
I've also taken a version of the HADB driver and stripped it down just to the climate domain in order to tinker with the way it handles thermostat setpoints. Don't hold your breath waiting for me to "fix" anything, but I'll certainly pass along anything I learn.
