Hey guys, the answer is drilled discs with good quality pads, anything else is a compromise.
Grooves or slot disc should only be offered on pre-cast discs as they are not physically suited to being drilled because of heat stress /ubbthreads/images/graemlins/blush.gif although I have to say they are still offered on the market /ubbthreads/images/graemlins/frown.gif Quality drilled discs are cast, not drilled after /ubbthreads/images/graemlins/tongue.gif
You are partly right Chris, although drilled discs also take glazing from the pad surface.
The main benefit of drilled discs (apart from partial deglazing) is getting rid of the heat from the pad/disc surface - this is where it is far superior to the other offerings, taking the heat into and out of the disc rotors.
As for cracks in the drilled parts of a proper cast drilled disc - it's all down to maintenance. I have 380mm drilled discs with 20k miles, including 11 trackdays on Sport Yellow Pagids, and they are slighlty worn but still mint.
Every 2k miles I just take of the wheel, take out the pads and floating disc and clean all the holes and rotor. With the pad just take a Dremel or hard sandpaper and take of the glaze and shampfer the edges.
If you do trackdays on drilled discs, do expect DIY maintenance (or heavy servicing bills). If you dont spend this time on maintenance, dont buy Porsche/Movit/Brembo brakes with performance pads - unless you want them to crack after 6-12k miles, choice is yours guys /ubbthreads/images/graemlins/wink.gif
BTW with a performance caliper/disc/pad I use Castrol SRF 4.1 as a minimum, coz that reduces heat thru the pad as well.
Andiroo