I have them and have had them for just over 2 years. They do work. The brakes stay much cooler than stock thanks to the opening to vent heat and aid in cooling. What does this help with, braking performance. I have no substantiated data to say if they stop in a shorter span, but they mated with the Mugen pads (supposedly made by Project Mu) feel GREAT. And braking feel felt much improved over the stock rotors and pads.
I am soon going to be replacing my front rotors with some DBA Series 5000 2 piece rotors, just waiting to hear back from the company as to how I can place the order. The main reason, weight. With the aluminum hat it should shed quite a bit of rotational mass.