So after reading on all the issues in systems without a C wire, quirks with its learning ability, and the data gathering, I've decided not to go forward with the Nests. That being the case, I'm trying to figure out what t-stats to get.
I need programmability, wifi access, and power that doesn't have to leech from the system (battery is fine). The ability to add remote sensors would also be nice but isn't critical. I don't care about remote access, and I'm fine with function over form (i.e. I don't need toys like touchscreen if there's a cheaper model without it that performs just as well).