Masnaka,
Depending on your MC, although I've done both ways with little or no known problems. How ever if you are using the Corvette 7" Booster (actually made for 4 way discs) really works well.
Slotted and Drilled: Baer and Wilwood both advised us to never use "Drilled" rotors as each hole acts as a heat sink and can, (and will crack like a heated marble dropped into water
) Two road courses and I had to junk a brand new set of rotors.