I'm in the process of looking for a sub-zero synthetic sleeping bag for some of my longer outings in cold, moist conditions. I do a lot of backpacking and mountaineering in NH and on numerous occasions I've lost the loft of my down bags.
I currently have a -40 down bag from EMS. I wouldn't have bought it accept for the extreme deal… picked it up for 99 bucks at a local EMS and I actually love the bag. I also have a 25 degree down bag that I use in the fall.
I'm having trouble finding a large selection of -20 synthetic bags though. Any recommendations?

