No doubt Gor-tex doesn't breath all that well. It merely breaths better than rubber.
As to wool insulatuing better than polyester fleece, the science and all prior experience (consistent with my forty years of monthly experience in the upper mid-west and Rockies) is that polyester fleece retains double the insulation value of wool when equally wet/damp and dries out much quicker. The subject is easily researched. Fleece is the choice of high mountaineers and polar expeditions - U.S., Japan, Germany, China, England. Not to mention the advantages of fleece in terms of abrasion resistance and field maintenance. That's why all those nice surplus wool garments are on the market; they are clearly second-best. Troops inexperienced with cold weather might get in trouble by failing to vent/keep cool vs. more experienced troops in wool. Any way, who was in wool? We don't issue it anymore.
TAL