So a while ago I went skiing at Sutton with several other people. It was hovering around -20 the entire day. Between the triple diamond trees and double diamond bump runs, and getting lost in waist deep snow for almost 2 hours and having to climb up the mountain (long story), I was really working up a sweat.
At end of day, I found out my mid layer (100g primaloft) is completely soaked in both elbow area, I was literally squeezing water out of the insulation, probably from snow getting in. Thinking back I didn't really feel cold at all, maybe a little chill on the lift later in the day.
Gotta say I was pretty amazed by its insulation property, if I had my other down vest on (which I took off earlier in the day), it would probably be useless with this much water in it, and cause some serious problems.