I'm using an Osprey Atmos 50, which is a slightly heavier version of the Exos. External frame? Looks internal to me, and frankly, does a superb job of transferring weight to my hips.

I've got some back problems, and absolutely need to have as much weight as possible moved to my hips. I went through four different packs before trying the Atmos (couldn't find an Exos locally). The Atmos was the first to truly take the weight off my shoulders and put it comfortably on my hips.

But let me say this: the pack person at the shop said I should wear a medium; I looked at the load lifters once the pack was loaded and on me, saw they were horizontal, and went with a large. I don't know if Osprey's measurements are off, but there's no way you can get weight off your shoulders with load lifter straps that aren't anchored high enough.

No problems with bouncing, shifting, or not moving with me.