Any disc with holes whether cast or drilled can and will crack under very heavy use.
Alot of manufs are using a groove as this helps the built up gasses under the pad to be drawn away from the disc. to help prevent fade (Fade is when the gas between the pad and disc builds up so much the pad no longer touches the disc.)
A drilled disc has holes for cooling which force the air from the outside thru the vents onto the pad having an opposing effect. (air is pushing against the pad stopping the gases from escaping.)
Back to the post, Ihave been looking for discs for a while but haven't found any as they are totally different from ep3 and rsx
Even pads are not easy.
If anyone knows different post it up..