Gregory z55 Rocks!
I bought this pack just over a year ago. Last summer I fit in four trips covering a total of about 100 miles. Attached pic shows pack during a 45 mile x 6 day trip through Wyoming's Wind River Range. I carried slightly over 30 pounds on this trip and have to say that this pack rocks! ...it carried all the gear/food/water that I need, handled the load nicely, was comfortable on the hips, etc. Most pack reviews put this bag in the 3 day range but, for me, this bag will easily work on 7 day adventures. Gregory says max load should be 35 to 40 lbs and that seems doable. With my old external frame pack I used to carry 40+ lbs but I'll be carrying 30 lbs or less from now on with my z55.
p.s. I liked this pack so much that I bought my girlfriend the Gregory Jade 50 (women's equivalent to the z55).