A big plus 1 for the Kifaru. They are expensive, no getting around it, but you won't be able to wear them out. I have an Express with an E&E and a couple of side pockets that I'll put on or take off depending on how much room I need. As polack said, the Maurader is pretty close to what you described. Kifaru has interior pockets that attach to the molle webbs or you can use any manufacturers pockets that use standard molle.

The E&E is also a pretty cool setup. Attaches to the larger pack to increase capacity, pulls off quickly and has its own shoulder straps so it can be a stand alone small day pack. You can't go wrong with it.