And now I have to eat my words. I just tried the new version of the Osprey Atmos 50 pack this weekend, and I think it may become my go-to pack. If I had to classify it, I'd say it was an external frame pack: you can see the frame, and it has a trampoline backpanel. However, it's not the old aluminum-pipe frame, with a three-quarters length pack bag pinned to it; it's small-diameter aluminum with an internal-style packbag firmly affixed to it. It doesn't have the "bounce" usually associated with external frames, nor does it move against you when you turn. The packbag is an uncluttered design that has all the features I use, and none that I don't (except for ice-ax loops; not that many snowfields and glaciers in Ohio.)

As I looked at other Deuter and Osprey models, I seem to see a lot of trampoline backs with frames buried inside the pack - a perimeter frame, usually, instead of the old X-style stays or single stays. They look like internal frames, but they have some of the structural advantages of external frames.

What I learned (talking to a visiting friend from Virginia, who works in an outfitter's there) was that the Osprey Kestrel and Deuter ACT Zero packs did not fit me as well as I thought. While the adjustable torso length could be set right, the problem came with the load lifters: the frame itself (the lenght of the back of the pack) was too short, and as a result, I was getting a zero-degree (or even negative) angle between the frame and shoulder straps - which was why I could never get the load entirely off my shoulders. (At 18 pounds, it never got truly uncomfortable, but my shoulders were a bit tired at the end of the day. I thought I was just out of shape.) The Atmos frame was a couple of inches longer, and I now have a good 45-degree angle between the shoulder straps and the pack frame - and the load can come entirely off my shoulders.

So, now I'm starting to think that it may no longer make sense to think of "internal v. external" but instead to simply say that you need to get the pack that is most comfortable for you. The lines between the two types appear to have blurred considerably, and the pack makers seem to now borrow freely from the best of both styles to make some "hybrid" packs that don't fit easily into either category.

As I found out this weekend, you're never to old to have an "Aha!" moment (or, in my case, a full-blown Homer Simpson "Doh!" moment.)