I'm looking for a new backpack in the 50-60 liter range, for carrying loads in the 20-30 pound range, but capable of occasionally going up to 40 lbs. I want at least some metal internal framing (allow, aluminum, whatever) but I want something lighter than my giant traditional style Gregory. Preferably in the 2-3 pound range. I'm on the tall side of a medium in most backpack fits, and a pretty solid medium waistbelt, so no fitting issues, so no unusual fitting issues.

Suggestions? I'm really liking the look of HMG's Southwest 3400 but I'd like to consider other alternatives before I make any decision.