I forgot to get back with you: I never thought about having the wrong size. Also, since my previous experience with it last year, I've lost 50 pounds and 6 inches around the waist. While preparing for a 4-day trip I'm taking in a couple of weeks, I found that the Deuter ACT Lite 50+10 wouldn't hold everything I plan to take. So, I went back and tried the Atmos 50 on - size large this time - and it fits completely different (or I fit it different; not sure which.) I'm taking another chance on the Atmos 50, which does hold all the stuff I'm taking. If it works well on the upcoming 4-day trip, I may even give the Exos series another chance, although the one I loaded with sandbags still had the same load transfer problems. (I probably need to drop a few pounds out of my current gear set, then try the Exos again with my gear instead of sandbags.)

The Atmos really is external frame, though: take a look through the mesh, and you'll see the bow-shaped cross-pieces; you can also see the frame where the pack and mesh wraps around it (they used a sewn attachment, instead of the clevis pins and wrapped mesh on the old externals.) None of the frame is buried inside the back of the pack bag. The comfort key is still the drum-tight mesh against your back.

However, I will admit that with the proper size, it performs a lot closer to an internal frame than an external frame. It may not be truly fair to call it either; it may be an entirely unique "hybrid" of both styles, with the advantages of both and few of the drawbacks of either. I'm taking it on a 4-day trip in a couple of weeks, starting with a 28 pound load; I'll try to remember to let you know how it did.

Thanks again for the tip about the angle of the load lifters. My first one was a medium - and the lifters were flat. That may explain the settling I was experiencing.