I have an Atmos 65L that I hiked 200 miles with this year.
It is a good pack, but there are some things I don't like. It squeaks quite a bit, like fabric rubbing on some padding, but I can't seem to eliminate it, and it bugs me. It is a little thing, but after 18 miles the little things add up.
The hip belt pouches need to be just a little larger, it would make the pack much more user friendly not to need to shoehorn stuff into them.
The double entry side mesh pockets are stupid. I store my water bottles there, and you have to be very careful of their placement or they can fall out. Also, it is a bit of a contortion to reach those pockets. This is probably my biggest gripe. If I use this pack more I'll probably sew the one hole shut.
It is also relatively heavy at over 3 pounds, stripped of extra straps, ice axe loops, top compartment. There are lighter packs to be had.
If I go longer this year I may pick up a ULA Circuit or a Z-packs pack.