Have an older Jam model and the durability is fine--it's made of sturdy fabric rather than superlight silnylon or other light but abrasion-susceptible cloth.
Comfort is also very good, but I have to emphasize the fit needs to be perfect because back length is not adjustable. Bbeing frameless the top comfortable weight is in the mid-20# range; more than that and things go south.
I tend to prefer light packs with light perimeter hoop frames (e.g., certain ULA models) but a frameless is fine for mild season shorter trips. I would not buy a large frameless pack because it would hold more than it can support and might not have a good compression system for less-than-full loads (frameless packs work best when stuffed to capacity).