Thank you. I've read a pile of articles since I posted the question. Some seem to be results of research others someones opinion without facts to back them up. I think I've sifted through most of the BS. It seems gassing off the old style pads was the reason they first went to drilled rotors, now with metallic and semi-metallic pads it's no longer a problem. Even NASCAR is getting away from drilled rotors although they still use slotted. They also change the brakes after a days driving.
Then there's the formulas of how much energy it takes to heat a pound of steel compared to a pound of air, the coefficient of friction in X material compared to Y material Blah blah. They all seem to agree about the cracking problems though.
When I took my front suspension off this week I was surprised to find the left rotor and pads grooved. I measured the rotor and the depth of the damage, to lathe off the rotor past the damage it will end up thinner than minimum, I'll have to buy new. The drilled ones look nicer but I'll save the money and buy stock replacements.
