I've also been told by people I know About Nests crashing and turning off. [edit: yes, anecdotal but it's not an unknown event] This is completely unacceptable in a Northern climate. No, it's not the only failure mode for a heating system but I have zero interest in adding another point of failure for the sake of having a cool device. Frozen pipes is a serious business.
That was my first thought; if I owned a Nest and it stopped working for 2-3 days right now where I live, I'd be in big trouble especially if I weren't home to get a space-heater to temporarily offset the issue
