Hi all. Looks like there's lots of good discussion on the New Osprey Exos backpacks. I would like to add a few comments:
Timothy, the Exos 46 is approximate equivalent in volume to the SMD Comet. As you know the actual usable volume of a pack can vary, despite the stated volume. I find the Exos 46 and Comet to have enough volume for a typical lightweight backpacking trip, and can be stuffed to carry the extra food for an extended trip. I managed to get food and gear for an 8-day trip into the Exos 46.
Joe, comparing the Exos with the GG Mariposa, SMD Comet, and GoLite Pinnacle is comparing apples and oranges. I put packs with removable stays into a separate category. With stays in they have an internal frame, but they don't have the comfort and real load carrying capacity as a pack with a built-in internal frame, like the Exos. For a little extra weight you get more comfort. It goes up from there, eg with a Granite Gear Nimbus Meridian you get still more comfort with a little more weight, etc.
Ashley, I would judge the fabrics in the Exos packs adequately durable for lightweight backpacking, with heavier fabrics and reinforcements in wear and stress areas as needed. But they are not as tough as Dyneema Gridstop.
Roleigh, I don't have a Bearikade, so I can't give you a definitive answer. The reason for the hip sizing is the bottom of the pack's frame is contoured to cradle your hip, so they list the maximum hip size each pack will fit.