I'm getting ready to purchase one of these pads and saw they have a mummy version too. My initial thought is I can see myself slipping off this pad more than usual if it's mummy shaped and it's possibly not worth the modest size and weight savings? Anyone used the mummy style? If so what were your impressions?

Also... anyone know who's got the best price on these right now? REI wants $105 for the rectangle. With their return policiy it's hard for me to buy anywhere else, but if I can save a little dough I might!