Eberlestock makes some pretty solid packs. Have had the chance to play with a number of different models I can tell you that you won't go wrong purchasing one. Yes they are expensive and yes the are purpose built for military users (although they do have a good hunting line as well) so they may be overkill for some.
I don't know what your actual application will be, but you mentioned abuse and long distances. The Eberlestock will do the job, do it well and hold up to all but the worst you can throw at it. When it comes to survival and field equipment... You get what you pay for.
The moddels you played with, were you able to attach your sleeping bag and tent externally? That is an important consideration, as it will be my task to carry my own bag and the family tent. Also, in one of the side pouches made for a bladder system did you put a hydration system in there, and how did that work out for you? Sorry, for the plethora of questions, but I have finally found someone who has used the system so I am interested in as many specifics as you are willing to provide.