stress fractures in ANY rotor probably wont happen in any of OUR cars. In order to reach temperatures high enough to compromise a rotor's (especially a decent rotor's) structural integrity, you'd have to be running it up to 90mph, hard braking to 5mph repeatedly for hours. Its probably only a real concern in REAL race cars like LM, WRC, ect. I've never heard of anyone cracking a drilled rotor in any street/race application.

But yeah, the dimples are supposedly stronger. I personally doubt it makes a difference.