Not (real) heating but cooling. And done pre-Hubitat. I have a 2-storey townhouse with poorly designed HVAC. The air-handler is upstairs, the vents closest to the air-handler are upstairs, and the return is upstairs. Thermostat is upstairs.
Master bedroom is downstairs. Sounds like a recipe for uncomfortable nights year around? It was.
Switched the thermostat to an ecobee3 (~5.5 years ago) with sensors and set cooling/heating profiles to use downstairs sensors at night. Helped a little, but electric bills started running real high.
About 4 years ago, I put an in-duct blower in the 12" duct going downstairs and wired it to go on & off when the air-handler blower went on & off (used a current sensor switch and RIB relay). This worked fabulously. I have balanced temperatures throughout the house.
Late last year, as you know, I swapped out the ecobee for a z-wave thermostat and a bunch of temperature sensors. Still continues to work fine. I don't "use" the thermostat's own sensor - just averaging to nudge the thermostat either way.
My average heat pump run-lengths with the ecobee were 16 mins. WIth this setup, I'm around 18 mins (and there are fewer runs).
Here are the current temperatures - the upper 4 are all downstairs and the lower 4 are upstairs.