Ok, the Nest arrived this morning and I have it hooked up. Installation was painless. After powering up and turning the dial it does control the stove feeder. I don't have the stove fired up yet for the season so I can't offer much info at this time about the actual heat control of the unit.
Here are my observations from the setup of the device...
1)it does have the ability to learn how long it takes to reach the higher set temp after a setback and get the house to that temp by the scheduled time.(True radiant setting)
2)Coal is not officially listed in the heat source setup, but it appears the "Radiator" or "Radiant heat" settings should work just as well.
3)The wifi control from my iPhone works great, the app has nice controls and gives lots of info. I have only tried controlling it from within the house over wifi so I'll need to test the control when i'm out and about and not on wifi.
4)The MAX setback temp is 70(or less), which could potentially cause big temp swings if you like it really warm. The "true radiant setting" is supposed to eliminate temp swings/overshoots. Others have stated not to setback more than 2 degrees or you get big temp overshoots. I will report my findings on this issue once I fire up for the season.
Issues could be changed or tweaked in time through software updates I would think. I have read many reviews of the nest and it appears the people who developed it and the software do listen to customer feedback at least somewhat, so any issues I have I will be reporting to them in hopes of getting features that may benefit coal systems.
This is my update for now....