I have an absolute strap on my Imago and although very comfortable I've noticed that when I have a few heavier items in it that it doesn't sit as comfortably when I have the bag resting against my spine with the strap across my chest.
The reason is twofold, I am 6' 5" (195cm) and in the arrangement described above there is slightly more length required on the side of the strap going around the front of my body than behind (I hope that makes sense).
The result is that the edge, which is not as well padded, rather than the centre of the absolute strap is sitting on my shoulder. I have adjusted the length of one side of the strap to make it asymmetric but I have very little to play with given my height as doing so makes the bag sit higher.
A potential caveat for taller people but certainly not a showstopper.