Ummm, how do you get that...

12 millimeter = 0.472 440 945 inch <---- From Online conversion

This 0.47" will make a difference, however not a "huge" difference as you suggest... From my calculations, it will give an increase of 19% more force over stock.
With the BBK it will yield an increase of 61% that's an extra 42% more braking force than stock...

Soo, as I was saying, I HAVE an EX to compare to, so U can't tell me they are that much better, because I have one to test against, and my experience speaks more than your suggestion...
Yes, they are better, but not by a large margin, and certainly not by more than inch... Let me guess, you have this conversion that is why you are suggesting it even though IMO I don't think it's adequate...
With the Powerslot BBK, the specs are:
12.00" (304.8mm) VS 9.45" (240mm) Stock

So, the powerslot rotors are a full 2.55" larger than the DX brakes, and 1.69" larger than the EX brakes...
While you suggest to do a conversion and get a whopping 0.472" larger than the DX brakes... I don't see where this is a better idea than getting a BBK?