Thanks esshup.
I don't want to test the freezing theory either! Unfortunately I have seen too many episodes where I left water in a system because I had several more weeks of work to pursue and the meteorologist said "34" for the low and we hit "28"!
I think I will take your advice and go with brass valves for most of my future projects.
(Even though I am south of you, my systems still need to be drained for winter. I was just trying to determine the "marginal" benefit of the brass.)
