After a huge amount of fiddling around trying to get my J7's right, trying different pads compounds and rotors, I finally settled on the standard Avid pads with ordinary round Hayes rotors. I tried a whole lot of different rotors and pads but found that in the end, it just came down to .........>
The trick for me was setup. Making sure that the pads only contact the rotor braking surface and NOT the arms as well, doing the CPS washer trick like xsl_will said, and most importantly....breaking the pads in slowly and correctly, which means not going straight out and hammering the cr4p out of the brakes and pads when brand new.
Getting the pads aligned on the rotor properly when setting up, making sure that everything is clean and working correctly.
Mine are silent, except when wet. They squeel when wet, but that goes away as you brake and the pads dry the rotor surface.
R.