I have one of these, my opinion
it rips out along the armpit rather quickly
it's VERY warm, I wore mine in everything from rain to snow and never worried about getting cold, if your armour fits closly it won't fit over one of these, it costs near a hundred bucks. do yourself a favor and have someone tailer make you one it isn't worth the money for the time it takes to repair it.
also you may have to add grommets all over it just to let the hot air out for summertime fighting. I have a 42 inch chest and the smaller size is the tinest bit too big for me. Currently I am on the market for another one that looks better and works better
so far the best price i can find for a gambison that at least looks a heck of a lot better is
http://ourworld.compuserve.com/homepages/gildedlily/gambeson.HTM but i have never seen her work up close