I got this pack just before a 4 day tour this spring, and I quickly became aware of the design flaw that dennis mentioned. The air intake filter is a 5" long rigid part directly on the crest of your shoulder, preventing the strap from wrapping smoothly over it. After 4 days, my left shoulder was hurting so bad, I had to carry the entire weight on my hips and right shoulder. I don't see how a smaller size could help much, but if you're fixed on getting this pack, try it on fully loaded in a store first!
In addition, the straps to secure ice tool shafts are the equivalent of little rubber bands. One good crash and those puppies are gone. I don't why they skimped on the tried and true here.