Again, it really depends on what you want to carry and what type of abuse you anticipate. On trail, you can get by with much lighter packs. I have a few different Kifaru packs, and they are heavier than most backpacking packs, but they've also been through more rough conditions...stepped on, thrown out of trucks/helo's, ratcheted down in a C130, sat on, pulled, kicked...more abuse than most packs will ever see; Kifaru hasn't failed me yet after too deployments.
However, I haven't tried a true backpacking pack since my early 90's Mountainsmith until recently with the Osprey pack. I'm quite impressed; I doubt it would handle the abuse of my Kifaru packs, but it's been pretty good off trail scambling and bouldering. I've been pretty impressed with it; good suspension, very lightweight, some nice features (I like the suspension, hip belt pockets, I like the side pockets for water bottles even though it has a hydration pocket/port; and the stretchable pocket on the back for jacket or pullover).
Let us know what you decide. The Osprey is just something I'm happy with, but the size is about perfect for you. I carry my essentials and have extra room to carry extra food or climbing gear; it would even be a good 1-2 night pack for lightwight camping.
ROCK6