In reply to frankor:
Frank,
If you're a climber, there's no reason at all to use a military pack. As Kate said, a climbing pack is called that because that's what it's designed for.
Having used both for their appropriate purposes for many years, I wouldn't dream of using my work pack climbing. If I wanted to take ammo, rations, water, cam nets etc into Coire an Sneachta or Cwm Idwal, then maybe, but best stick to a proper climber's pack.
If you're more of a Ray Mears-type rather than a climber, go for plain green rather than camo. Makes you look less like someone you'd cross the road to avoid if you're with the wife and kids...