I bought the Atmos 50 for three-day weekenders. My other choice was a Gregory G-pack. The Airstream design makes this pack float on your back. The water bladder compartment (and the main compartment) is bowed by the frame, so you get cheated a bit on bladder capacity. I found that packing in "rolls" from the outside toward the center works well (with the smaller "rolls" in the center over the frame.)

I wore this pack for an overnighter trip on the AT in the TN/NC mountains. It was awesome to wear! My back was actually cool with the new airspeed frame!!

My pack weighed 18lb, I think it could hold about 10-15lb more before it would be uncomfortable. The hip belt pockets were great for a bag of gorp although you can't stuff them once you cinch down the belt. There are tons of options...pockets, straps, a whistle on the chest strap, and a nice sleeve for your Camelbak, even the option of hanging your water bag in the airspeed frame. The only drawback is the airspeed frame leaves a huge hump in the pack so it takes a little thought in packing. Otherwise, great pack!!

This pack is fantastic. I am climbing Colorado's fourteeners with it and barely notice its weight at altitude. The Atmos 50 is well organized with easy access to its various compartments. The suspension system keeps it away from the back, which prevents overheating. There is plenty of room for food, cold/wet weather gear, and other backcountry essentials. The ability to carry a hydration bladder within the pack is very convenient. I highly recommend the Atmos 50 to anyone looking for a comfortable, lightweight pack for their trekking adventures.

The makers of this pack paid a lot of attention to the small details like fasteners, pockets, seams and fabrics, which is appreciated. The ventilation through the meshed shoulder straps and belt combined with the open mesh back make this pack very cool. I also really appreciate not dealing with that clammy feeling from putting on a sweaty pack after taking a rest. But the very bend in the frame that allows that airy gap behind your shoulders also limits the interior space of the pack, and fitting large items becomes difficult. Also, there is limited adjustability in the shoulder straps, which are sewn in, so if you are in between sizes, as I am, you're kind of screwed, since the pack will either be too long or too short (in my case, just a little short). Nonetheless, it's still a comfortable, durable pack, just not quite a perfect one.

I just went on a three-day backpacking trip with a friend through the Colorado Rockies in the Mt. Evans Wilderness area. It was probably one of the most beautiful things I’ve experienced. The incredible Atmos 50 pack was awesome, it held everything I had and I went 5 hours non-stop with about 40 pounds and it still felt weightless on my shoulders and I’m not a big guy. It’s also compact enough so that you can use it as a carry on when flying.