Dang, I missed this thread?
Interesting tests on the ducts. I agree with Porschefile (why wouldn't I?) that you really need to get the temps right after a hot lap. I had a Zionsville radiator in my 330...peak temps were a tad lower but the biggest benefit was that the water temps would decrease much faster after a hot lap and I could run longer at that peak temp vs the OEM radiator which would begin to become overwhelmed after about 25 minutes.
The bimmerworld E46 backing plates had a flange on the side which was very close to the inside of the rotor hat. According to their website (Turner or BW) this reduced air leakage and directed more air towards the center of the rotor. Then the air would be passed through vains between the rotor disc surfaces which would cool the rotor better and more evenly.
I'm not an engineer but that design looks like its only cooling the back side of the rotor. Have you noticed uneven pad wear? I would imagine the outer pads are wearing faster if that's the case.