If you want a panel loader, the new Six Moon Designs Traveler might be the one for you. Get the optional stays because the load lifters don't work without it, and with the stays it works great up to 35-37 lbs. You can always remove the stays for really light loads. I have their Comet pack and absolutely love it. If I were getting a new pack, though, I'd go for the Traveler.
_________________________
May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view--E. Abbey