In scouts (in the 80's) we mostly winter camped. We called these pants "German Army Pants" and they were *the* must-have gear item. We all wore them all the time, with our belt knives and Silva compasses and Peak 1 stoves.
I don't think any of us actually knew where the term "German Army Pants" came from, but we all had them and they were awesome. Lots of mobility for walking, lots of warmth for standing around camp, seemingly never staying wet, never getting clammy, and they even shed snow nicely. When I started doing winter outdoors stuff again in my 20's, they were the first thing I thought of. The only reason I don't own a pair now is that I already come off as too much of a hillbilly for west coast sensibilities.
Just like the antique climbing suit used by Hillary being pretty much as good as the best modern equivalent, these pants are an example of old technology that really worked then and really works now!