Slotted is not an issue like drilled.
Drilled weakens the rotor and leads to cracks.
Maybe it is not such an issue in a very high end rotor, but certainly an issue for normal rotors.
Any rotor can develop cracks, drilling makes it much easier to happen.
Better metal and construction also greatly help to reduce cracking.
Under engineered braking systems can lead to more heat, and cracking of the rotor material also.
The slots might help keep the pad material "clean", at least that is what they claim.
I lean more toward the high quality rotor side of things.
The cost difference between a Rabestos "service grade" and "Advanced Technology" is not enough to make me go cheaper.
I figure that I save money be doing the brake job myself, and using high quality components throughout is worth it for stopping.
Stopping is too important of a function.
Does that EBC rotor have painted non-friction surfaces?
It looks like that "hat" is painted.
If the paint holds up to the heat cycles, that is another "plus".