Aloha,
I'm certainly more inclined to use a top end pack over a camera bag, biggest issue for me though is waterproofing my gear. the H2o bag here is pretty good, fits almost all of my Pentax 645 system in it, but the straps just suck for carrying around thirty pounds of camera gear especially after the comfort of a high end bag.
Everything you see in the picture (all 105 lbs) fits into the blue arcteryx Bora 90 in the picture, even the lowpro h20, then I'll set up a base camp and just carry the h20 in the bora if I am moving over longer day hikes over tougher trails, or no trails...
Another advantage of a regular backpack is you just look like some broke backpacker, and your camera bag with $20,000 plus worth of camera equipment is not a target :-)