Why would you go from a zero degree bag to a 25 degree bag for "winter"
hiking ?
I would imagine the clothes you would have to carry and use to make up
for the difference in sleeping bag rated temps would outweigh any
advantages of using the 25 degree bag ?
I have, and have used extensively:
1) Smartwool top and bottom.
2) Go-lite C-thru
3) Under-Armour.
I would rate them in the order I put them. Although I like the Under-Armour
best for motorcycling because it allows me and my outer clothes to move
easier about the bike, etc..
In my personal test I did before I did some cold winter canoeing Wool
offered some warmth factor when wet. Polypro and C-thru offered no
warmth until almost totally dry. Although I didn't time it, I believe the
Smartwool also dried faster. But that might be because after my self
induced dip in the cold creek, I took it off, wrung it out the best I could by
hand, put it back on along with my outer layer, and proceeded to make
camp in relative comfort in mid-thirties F temps. I was unable to do this
with Polypro and C-thru. I had to get in the safety tent and shiver awhile.
Don't do these kinds of test alone. Have a safety shelter with plenty of
warm blankets, and hot drinks ready so if your safety Doc thinks your
getting hypothermia treatment is easier and close. Mine was a ex Navy
corpsman so I felt pretty safe doing these just to find out test. Lots of
myths out there and unfortunately too many manufactures that at worst
over-hype and mis-represent their product(s) while not informing us about
what it won't do.
Try finding any unbiased test results and you see why I learned to test it
myself when I can.
I am a big klutz and have managed to get pretty wet in temps well below
freezing, so I know it can happen.
I vote for wool. The best you can afford.