If you believe what the dudes on the weekend car TV shows say, the drilled and slotted rotors are much better at expelling "gasses" during the braking process and these rotors are more effective. I have never heard anybody say anything about them being more prone to cracking.

Since I think you are referring to your track car, the TV guys also point out there are many brake pad compounds from pure street to pure track (for instance, EBC's Blue Stuff, Yellow Stuff, Green Stuff, Red Stuff).