keeps you warm regardless of how wet you are
Yep, it insulates even when wet. But it's a real
bear to get dry sometimes.
it breathes VERY well when your moving fast and outputting lots of heat/steam/sweat.
Another huge advantage of wool, why I wear wool socks for summer work and hiking, wool maintains a level of cushioning even when soaked.
As far as the poncho question, I wear a military surplus poncho with the grommets and snaps. It's come in handy quite a few times in mountain monsoon rains and hail storms. Several different ways it can be used to protect from rain:
- when day hiking, it covers the entire pack
- hiking with a frame pack, it can somewhat protect the top of the pack if snapped together a certain way
- when stopped with a day pack it's easy to sit cross-legged with daypack on lap, and have the poncho covering everything. Eat lunch in there, take a nap, whatever.
- when sleeping, poncho snaps around sleeping bag to protect from dew or light rain. Most of the time though I simply lay it out as a ground cloth.
I've only used it to build a shelter a couple of times in real-world situations:
Once, I used a stick in the poncho 'head' to hold up the center, and staked each corner. Two people with ponchos can snap theirs' together for a decent-sized shelter. Spent one rainy night like that with two friends and their ponchos.
And once I removed my boot laces and tied the poncho between two trees. Used the frame pack as one 'wall'. That was a hellaceous hail storm...
I carry a lawn-sized trash bag to cover the entire frame pack when not wearing it.