I work at an outdoor outfitter and was poking around various dealers sites and found some cool new products!
Kelty has started making military and camouflage packs.
I'm not super impressed with the military packs, but the camo ones would probably make the perfect bug out pack. They come in several volumes depending on how much you want to carry and how prepared you want to be. Several of them have integrated gun/bow holders.
Here's a link to the camo:
and here's a link to the military packs:
Here's my pick:
The Varanger can carry heavier loads and is top loading making it easier to cram more in there and there's no zipper to break after prolonged use. This pack has the ability to carry a gun or bow and has lots of pockets. I love having pockets because its so much easier to make sure you can get to the things you need quickly.
And, I guess the camouflage would be a benefit in a less than ideal bail out scenario.