I like the arc teryx. It's basically just another big, strippable and simple bag with a sleeve to hold a frame/folded pad. But it has these two horizontal dealies fixed about level with the side compression straps. Seemingly gimmicks, I thought about cutting 'em out. I stalled, and am glad. Cause they're pretty cool. When you've got the pack way stripped down and packed lightly, the stays hold the pack flat to your back when it's compressed- effectively countering the "Andinista-tube" effect.