My wife and I are thru hiking the AT in 2018. You guys have been great about helping me in our planning phase. I have read a dozen books on hiking the AT, including UL hiking tips, and I have watched hundreds of hours of videos on thru-hiking. So I'm not ignorant on hiking, just inexperienced. I'm almost scared to ask this question with all the UL info out: Is it a mistake to attempt to carry an Osprey Atmos 65L, and my wife carry an Osprey 50L????? I have only been able to try on a few packs. My first pack to try was The Atmos, with 20# in it. The REI that I was in had a second floor with stair access. I walked around in it for about 30 minutes going up and down the stairs and it felt like I didn't have anything on my back! I have been able to try a few other UL packs, but they were uncomfortable and it seemed like they were much heavier, even though they weighed up to 3 pounds less. Could it be that with when I tried on the UL packs I just didn't have them adjusted as well as the Atmos? I want to be UL, but the Atmos feels so good. Look forward to the input from those more educated and experienced than myself.