I think the thing that the RIBZ system does is that it is politically neutral in appearance. But it isn't flexible- it is a decent sized possibles bag, and one you can wear under a jacket. The problem is pockets in the older model one I've looked at were layered- I've never liked that, becuase unless you are packing flat stuff, you know that what goes into pocket A will take space out of pocket B, but that is a personal preference. And the whole thing is fixed. Yes, that saves weight, but I like being able to strip gear down to what I need.

As others have said, military-type gear has been doing this for a long time. I've had my MAV since 2005, and I've set that up with everything from slim pockets that hold basically my wallet, pocket items, PSK, FAK and a spare flashlight for when I'm just cruising down the river in a tube, to big pockets that when added to a bed roll and a bread bag are pretty much all I need for an over night. I can even, by removing the back panel and letting the strap out, wear it behind me, as a lumbar pack.

*shrugs* I'd rather get get the glare of hippies and have flexibility, but YMMV. I love the concept though, because it does move mass up front which helps to move your center of gravity forward some. Although I also have, when it is fully loaded, about 8-10 pounds in my MAV, which is going to move my center of mass probably a good inch or two forward. *laughs*