I'm doing fine with Foscam (960p and up, wired) and a Synology DS216play as the DVR. There are even cheaper ways than that too.
At the number of cameras I have (12), it's $550 more initial cost to do it with these Nest Outdoor ones than the Foscams+DS216play+2xWD-Red-4TB (with the detection areas set correctly, I have about 4-5 months of 'history'). Except I'll pay $0 monthly fee for all my cameras and to add a camera it's $50 less than the upfront cost of this (including another record license on the Synology). Side benefit is my recordings will never be in the cloud or anyone else's hands, ever.
Speaking of... I'm going to guess that I would need to sacrifice bandwidth constantly for each camera to record to the cloud with the Nest as well...
Just a whole bunch of "nope" with these Nests, if you're smart.