I have to second the PDGA tour bag. I hooked it up with some Quadshocks at the 4 corners (where the loops are at the end of the zippers for the large pockets) and it's schweet!!!

The straps stay open, are easy to put on, and the bag sits nice and flush on the back. The 2 drink pockets on the bag are a god send. Large enough to fit 2 Nalgene bottles. The only thing I don't like is the accordian dividers and would prefer a divider like the Rev bags. Aside from that it's a stellar set-up! ... and cheaper than a Rev+QuadShock combo. These bags are built extremely well.