Thanks @danabw, this is a great example of a recycling old equipment the right way. Channel it back into the community so it can be connected to another hub.
I changed to Ecobee a year (or two?) ago. I liked that they directly supported remote sensors (our therm is in a really bad location to choose when and how much to heat or cool) and used the Ecobee Suite with it at first. When the HE HomeKit integration was released I switched over to that. Have to say that I don't do a lot w/HE to control the Ecobee directly, mainly turn HVAC off if we get any leak notifications from the leak sensor under the AC evaporator.
Oh - most importantly, wife finds Ecobee easiest to control at the thermostat itself of any of the ones we tried. She strongly prefers to going to the therm to adjust if needed, even w/the app on her phone she still will get up and walk to the therm. Old habits die hard, I guess.