The newer model 2800 has an internal area and will hold more gear than the older style 2800. Our party has both models in camp. You would be surprised how much you can get into and pack out with the 2800 when you put it two the test. I packed out all 4 quarters of Rubblesph "little bear down" in one trip! (though i do think it was even cause he had the hide, head and backstraps). One of the guys in our party just bought the 4500 at the Tri-Cities SCI banquet....it seems to big to me for a 3-4 day trip, but if your going in for a week...its your pack. Attached are a couple of pics from each pack in action.