I'm an ideas guy but I don't have the drive to go produce something for myself so I figured I would throw this out there. The other day while was schlepping my plate carrier with front and back ceramic plates and full loadout with 6 loaded mags, my traps were aching like mad from the shoulder straps weighing down on me. The thought came to me that when I'm backpacking, even with a 40 lb. pack my shoulders never hurt, because much of the weight of my pack is being carried by the waist belt.
Since 1 lb carbon nano tube Level IV plates are a long ways off, why doesn't someone come up with a plate carrier that carries the weight of plates and your load out on your waist just like a modern backpack does? You would just need a polymer frame that twists with your torso but supports most of the weight of the plate on a waist belt, which could also be used to carry gear and would accept a holster, standard or drop leg.
If you take this idea and decide to run with it, I just ask that you send me one of the finished products when its done. I take an extra large vest so you need to produce one that accepts 11 x 14 SAPI's.