I just got back from a bit of light speeding, and I noticed this:

Bear in mind that I carefully warm these rotors up, I cool them down, and they have never seen a track day in their lives. And yet they cracked, just from a little bit of commuting and a little bit of autocrossing. My slotted rotors NEVER did this... I think we're going back to slotted, then. All that remains now is to contact StopTech and find out if I can get my money back, or if these things are unsafe or what. Guh.