The wool is great for keeping heat in even when wet. take it from an Oregonian, a very soggy one at times....The heavy wool pants you get at the surplus store work great if you are tree stand hunting, or not moving around much...the get really heavy when they soak up water....my favorite combo in 40 to 50 degrees and rain is long johnsor sewat pants, with a gortex shell rain gear over that, then the fleese pants. the layers allow your legs breathing room, you stay dry & fairly warm while stalking....if it gets too warm peel a layer off....i love wearing a thin wool shirt under my fleese with no rain jacket at all...the trick is getting it big enough to move around in...as long as you stay active and don't sit too long in the rain, you'll stay warm...wet....but warm...
you cannot beat fleese for being light weight and silent, but it does soak up water eventually and doesn't keep your body heat in like wool does. the only down side to fleese that i've found is that it catches burrs really bad...
the other option out there you should check out is "Saddle Cloth" it's a little spendy, but comes in a bunch of different cammo patterns, is very quiet, and wears like iron...i've got some fleese and saddle cloth both i've used for 15 years now...the saddle cloth day packs hold up VERY well....hope this helps....Kirk