In reply to Gaston Rubberpants:
I have similar experience but coming from a Osprey Talon 33 and switched to a Trion Pro. In my opinion light is only right when you don't really carry much. When you have heavy loads, a backpack with proper back system is much more comfortable.
Ok, I don't want to start the usual light-freak vs proper-backpack argument, just mentioned that around 30-40L, the ultralite choice is not obvious (and definitely not a joke). For below 20L it is.
About the Deuter Guide: I cannot cite it obviously, but if you go to the german speaking parts of the alps, you will notice the abundance of Deuter Guides.