Owned a first and second gen Nest with my 18 SEER Trane 2-stage heat/cool system with standard humidity pad and ~10 sensors in my homes. While both worked as advertised, after Google bought Nest and dropped further iOS integration with no intentions on HomeKit support, I researched for months and decided on the ecobee3 HomeKit and haven't regretted it (for those seeking better energy savings, more support, HomeKit integration, and integration with other systems I wouldn't look into Nest products). I was surprised as my energy bills in both my homes (NY and Berlin) have gone down significantly and the ecobee3 HomeKit is much more efficient and flexible than any other thermostat I've tried or researched.
ecobee3 HomeKit review:
With support for up to 32 remote sensors that detect motion, humidity, and temp, each sensor can be included or excluded in calculating overall temps and activation with Home, Away, and Sleep modes. Example, you can select which sensors to be included in "Sleep" mode and whether you want the system to take motion detection into account for determining the overall temperate ("Follow Me" settings will kick the system in if "All Sensors" are selected in determining the temp or if only those that detect motion).
"Auto-Mode" is fully supported with HomeKit and Siri. If your "Home" range is 68-74 and you ask Siri or Echo to set your home to 72 degrees, it will only kick in if the temperate is outside your currently active mode or if the degrees set in preferences differ enough (for example, if your home is 74 degrees and you ask Siri, etc to set it to 70, if 2 degrees is your differential it will kick in even if the temperature you requested is within your Auto-Mode range). 2-Stage Heating and Cooling, evaporative humidity system control, all types of heating/cooling system support, and having been testing it with iOS 10's HomeKit, it works perfectly.
Yeah, ok, sounding like a salesman. Just my two cents. Also noticed the GM build of HomeKit recognizes each sensor independently now and ecobee plans on updating the firmware so sensors will work with home security systems in motion detection and more independence (i.e. each can act as a fully independent module in their respective zones -floors - and rooms).
Also had a Dropcam when Google acquired the company and required an annual subscription for video recording. I used it for almost a year before cancelling and getting a refund for the remainder as I have Synology servers that come with surveillance support for hundreds of camera's (2 -4 licenses depending on sever, meaning two - four camera support, with additional camera support licenses costing a few bucks). Didn't see the point in supporting a system that Google clearly has no intention of supporting outside an even tighter ecosystem than iOS. If you're in the market for good indoor and/or outdoor camera's (IP, 2-way audio, night mode, motion sensors, etc.) I highly recommend Hikvision.