Ken Keel wrote a review of Arc'teryx Altra Backpack 75 - Men's - 4577-5248cu in on October 21, 2010
I just recieved my pack (Raven tall) yesterday and after a shake-down of all the features I'd have to say this is one of the best large volume packs I've come across.
I have not yet had the pleasure of abusing this pack with my gear and the envoirnment, but I do believe this pack will be able to handle everything I throw at it! This is a cavernous top loader with a suitcase style U shaped zip panel for easy access to the inside echo chamber. Adjustable shoulder straps - vertical and horizontal. One of the most comfortable hip-belts... and on, and on.
I was able to load my climbing gear (harness, protection and a 70 meter climbing rope), sleeping bag, ENO One-Link DoubleNest hammock system, cooking gear (stove and pot), clothes, food container, water treatment, jacket, and a few other odds and ins inside this pack with room to spare. 50 plus pounds and this pack did not even flinch after a quick cinch down on the compression straps.
I do believe that I will be enjoying this pack for quite some time. Thank you Arc'Teryx for a fine product. Also, thank you backcountry for great service.