I've completed some prelininary field testing of the latest vest prototype. Fortunately, the weather has been very cooperative -- and by "cooperative" I mean it's been bloody freezing here (8°F). It's been said that 2014 - 15 has been the worst winter in New England since 1978. That said, the vest is remarably effective in testing -- more than I'd hoped, actually. The most noticable thing is that my face, hands and arms didn't feel particularly cold. As far as I could tell, my circulation was completely normal.
As happy as I was, I see clear areas for improvement, and I'll be addressing these in the next round of prototypes.