right now I have an REI Flash. It isnt very comfortable over 20lbs. REI considers it an ultra light. wanted to see what other think are the most comfy packs. Looking for something between 55-65 liters. I have thought about the Osprey Atmos or the Osprey Exo 58
How much do you normally carry (including food and water)? A suspension has a point beyond which the load overwhelms it and it is no longer comfortable. So, to know what we like, we need to know your planned carry weight.
Normally I dont carry over 17 or 18 pounds but I am planning on doing a lot more desert hikes this year where water is scarce. Doing the Outer Mountain Loop trail in Big Bend in January. I have to pack all my water, so I am thinking some where around 30 -35lbs. Will have one cache. I did an over night trip last night and over packed my pack to see how it felt. It was uncomfortable. Shoulder straps were on my shoulders. The hip pads did nothing. My hip Flexors were hurting 5 minutes into the hike. I need a pack for when I am not ultralighting
In my opinion - and keep squarely in mind that it is my opinion, based only on my own use - forget the Osprey Exos packs (and the Talon, for that matter.) The suspension is not adequately supportive for a load of 35 pounds. Will it carry it? Yes. But for me, the hipbelt started to collapse at 30 pounds, wouldn't stay put, and wouldn't keep the load off my shoulders. You should be aware, however, that I've read reviews by others who claim it carries 40 pounds comfortably.
The Atmos would certainly work; I've used it at 30, and it never missed a beat. However, I'm just not a big fan of trampoline style suspensions. My current favorite pack (at least this week) is the Deuter ACT Zero 50+15. It's got a good, sturdy hipbelt, two aluminum X-frame stays, and well padded shoulder straps; at 30 pounds, the load never budged: it stayed centered on my hips, and I could shift weight between my shoulders and hips as I chose.
Another good Osprey pack is the Volt (60 or 75 liter versions available.) Good, sturdy suspension easily able to carry 35 pounds comfortably. I've used it, and really liked it - but there's no way I need 60 liter capacity; even my winter long-weekend load barely gets into the 15 liter extension collar on my 50+15 liter pack. However, if you can fill it up, it's a great pack.
The weights: Atmos and Volt are both right at 4 pounds, Deuter is 3.25 or so, and Exos is 2.5.
I can't recommmend the specific units I used, but they were different than the one I've linked to above. Maybe platypus learned something in the interim (?). My version had a sort of clip to hold it onto the waist belt, and in general the problem came when I tried to set the pack down or sat down on something with the pack on. The units hung down below the waist belt, of course, but with the little clips what would happen is that they would just come off the waist belt, and it was a bit of a PITA each time to try to get them back on. Ultimately I just carried them strapped to the pack anyway, and then just got rid of them.
*Maybe* these units would work better, as there's a continuous loop rather than a clip. But even still, whenever you take the pack off, they'll want to shift and slide off the hip belt ends, and you still really can't sit with these, unless you happen to find a rock or log that allows the units to hang down on each side when you do.
So maybe not such a good idea, but --- maybe it would work for you anyway, just so long as you're aware of the downside.
FWIW, adding more weight than rated generally worked fine for me with various backpacks, at least for limited distance/time, and water weight is exactly that --- you load up at a water source, then drink it down so the weight declines relatively rapidly.