I was wondering why only two, also. It could be that the OP has already read all the other threads, researched packs, and narrowed it down to these two. However, if this is still early in the search, I'd suggest taking a look at Deuter's line of Aircontact packs. After a couple of years thinking that the Osprey Kestrel line was my ideal pack, I've recently started using a Deuter ACT Lite pack and am finding (so far) that I like it better. Since the Aircontact is to the ACT Lite what the Aether is to the Kestrel, it would pay to spend some attention on the Aircontact if the OP hasn't already. (The weights are pretty comparable and both are equally adjustable, so you can compare based on suspension comfort and feature set.)