One thing that separates the REI XT-85 from most other mountaineering packs is it has a rigid metal frame around the outside and tied into the belt. It fits like an internal, but has some characteristics of an external. I find it very comfortable and I even use mine for day hikes most of the time - it pretty much never gets fully unloaded. It runs $289, but you can get 10% by signing up for REI gearmail I believe. I picked it up following reviews on Rokslide and Hill People Gear. I was looking at $600 or so for what I would have wanted from Kifaru etc.
I was really interested in the Wilderness pack frames, but found that I get no load lift from the MOLLE style frames. The REI is the first pack I've had with adequate load lift (and plenty to spare as well). Being able to really dial the pack in for any load is great. I'll probably not be putting more than about 80 lbs on my knees from here on out if I can help it, just getting to be too much wear and tear.