Agreed with everything you said.
Like I mentioned, Deuter makes awesome packs. Before I bought my Osprey, I was interested in the Race X Air. The mesh on the back means that your back never really touches the rear of the backpack! It's just a huge mesh vent that's awesome for airflow! Also, the straps are mesh as well!
The 2 reasons I got my Osprey is because the 3L hydration pocket on the backpack, and the hydration bag itself, never compresses. It's rigid, so there's never any pressure on the bag. This also means that when I put my 11" MBA in the hydration pocket, it's REALLY well protected. Also, my bag is 14L, which is close to the 15 litre backpack I was looking for. 12L would have been a tiny bit too small!!
Anything 14-20L would have been good for me, but I went for the 14 L bag because I wanted to try packing lighter!
The mesh at the rear of the backpack, and the mesh straps, probably make the Deuter the perfect choice, but my bag does a better job at other things (comfort, IMO).