Interesting photos of Baer cross-drilled rotors on a 1996 WS6..... cryo treating was required to extend ther life from 4,000 miles to 19,000 miles:
http://www.ws6.com/cryo.htm
He raced in the 150MPH Silver State Classic with those, I guess.
I've had the Baer slotted, cross-drilled, zinc-washed rotors on the rear brakes on my Formula for about 6 years and there's no sign of cracking, but I doubt they have much more than about 10K mles on them.