I have the Kata r102 as well; good for one D2x, plus space for three lenses, depending on what they are, and how much other stuff you carry (like a flash.) It's good if you know what you're going to do, and aren't going far. It does not transer weight to the hips, but it's so small, that you don't feel too much weight on your shoulders anyway, because you can't carry that much. I bought a Kinesis belt system a couple of years ago, and it didn't work too well for me, but the Kinesis bags have belt loops on the back and it's easy to tie them into the loops on the outside of the Kata - you can carry a water bottle, another lens, etc. They're even color-compatible (the Kata is black-and-grey nylon, the Kinesis bags are black nylon.) You could probably do the same with other belt-system bags. I think Kata got the padding about right.
One thing about the Kata is that it's pretty quick to get at the camera (it's under a special flap, and you normally carry it with a lens mounted) and yet it doesn't look particularly like a camera bag -- it looks like a book bag, or a college backpack.