One trick to cover your ass when using a Camelbak, or any other hydration pack, is to keep one bottle of water in the pack. Since you can't see the bladder, it's a rough guess on how much you have left, so it's easy to run yourself out. Throw a bottle of water in the pack as a reserve, and you'll never get caught with a dry bladder. I use them for hunting, cutting timber, running, hiking, and cycling (120-150mi rides), pretty much anything where I'd need to be mobile and need something to drink.
I've used Camelbak's for hunting for ~20yrs, kicking around through rather thorny brush. The pack insulation and shells are durable enough that you won't have punctures from "passive contact." Even falling down ravines, and one gnarly bicycle wreck, I haven't been able to puncture or rupture a camelbak brand bladder yet. I HAVE, however, punctured cans of pop/beer, and waterbottles in the thorny brush in which I hunt, so it's not like I haven't been poked!
i do but i find that after plenty of rehydrating beer i wake up really thirsty.........
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