I hike the mountains of AZ with a KUIU pro 2300. It has room for all my stuff, and the carbon fiber frame puts all the weight on my hips and legs, and the belt pad and the lumbar support makes it feel like there is hardly even a pack there. I mostly day hunt with it, but can occasionally need to pack out meet with it. I can load more on the system than I can carry, but I can carry about 100#. 63 years old and surgery on both knees from sports injuries in my 20's and 30's. I am very blessed to still hike any mountain that presents itself (still rock climb too), though I have learned the easiest, although sometimes slowest way to do it.