That EBC rotor would be my choice , certainly over mounting a second disc, in which I don't believe, the more after a member wrote recently he immediately took it off, unhappy with the extra unsprung weight.
http://forums.sohc4.net/index.php?topic=64964.msg712087#msg712087
I initiated a thread about a year ago about dual discs. My question related to the holes in discs affecting stopping power. I knew that it didn't but I couldn't remember why. I got the answer which then expanded to a fuller discussion of dual discs.
Essentially, adding a disc by itself doesn't increase stopping power. It takes the available power from the master cylinder and spreads it over a larger surface. THe benefit is less fade, less pad wear, and a more symmetrical feel to the fork, though this is a different subject. We had engineers in the thread with formulas and high falootin math and everything.
More and bigger holes also doesn't change the available power, it just concentrates it on a smaller area...and increases pad wear.
SO I got to thinking, for my riding style, which is fast but not hard on the brakes over and over, wouldn't I be better off going back to one brake, making it as good as it can be with a EBC rotor, pads, and maybe a more powerful master cylinder, which is the starting point of ultimate brake power anyway? Then I can enjoy the lighter front end, and lower maintenance.
If you're doing track days, or outright racing, or just want the look, then 2 discs is right. But for a street bike, without upgrading the master cylinder and rotor material, is there really much gain?
Personal preference. I'm going to give one primo set up disc a try for my cafe racer.