Don't forget the petzl euro style. I've since moved up to the 20 pounders, but I still haven't done any pushups. The MYO XP fit right in my pocket this past weekend, with a barely noticable bulge. Think about durability! I don't want to see you making the wrong decision here.
edit...ok so you already bought one. well, fine, you're carrying the rack next time, since your pack will wiegh nothing.