In agreement with what C.I. said above ...
I wear silk and/or polypropelene/wool combo underwear but the next layer or 2 is usually wool. It breathes well, warm when wet, tough and quiet. The extra weight issue is balanced out by it's quietness and comfort.

I have been shopping lately for high end camo that will serve me well from 45 degrees to 0 degrees. I'll probably end up with some kind of shell or unisulated coverall and then keep wearing the wool layers beneath as needed.
Or, I might invest on some of the really expensive wook camo that is out now....