Woot! I'm in. I'm a women's 7.5, but wear an 8 in athletic shoes. I picked the medium over the small because good circulation = warmth, so I erred on the side of a roomy bootie in case the small ended up being too fitted. I also got the Dyneema overbooties. I will report back here with how the fit is. I should note I also bought a medium in the Feathered Friends booties and that size has worked great. It will be nice to have ultralight booties!