My grandmother used to have blankets that used wool for batting. I think you can actually still buy wool batting. I see compressability as a problem. How large a stuff sack would a 0F wool bag take? The wool batting does not make a lot of sense now that there are much lighter synthetic batting materials that work well in wet conditions. I would reserve wool for underware. As underware, it really works well, in conjunction with a synthetic bag, if you are in VERY wet humid condtions.