Hello The Erkelbot,
I was part of the ecobee3 presentation last Tuesday.
To my knowledge, here are your answers:
(1) If you want to take advantage of the new sensors, you need to upgrade your SI to ecobee 3. They will
offer a discount coupon for existing users to upgrade ($79 of additional sensors value). BTW, the new ecobee3
can only be hooked to one device such as an HRV/ERV, humidifier, dehumidifier.
You can also keep your current SI and buy an additional ecobee3 (if you have multiple zones in your house for instance). You can then group them together if you want to synchronize some settings (ex. vacation, schedule, quickSave settings).
(2) The new ecobee 3 will use the same public API that I’ve used to develop the ecobee custom device at
https://github.com/yracine/device-type.myecobee. The custom device has additional commands over the default Smartthings integration.
For example, you can set your thermostat to ‘away’, ‘present’, ‘sleep’, ‘awake’ climates in the Smartthings UI or through some smartapps according to your lifestyle.
There are also many smartapps that I’ve developed that take advantage of all ecobee features available, such as
controlling your humidifer/dehumidifer via ecobee.
Take a look!