Just as an FYI, my Stoptech rotors look better after their 5 events so far than the 13" Cobra rotors looked after 1 day. The Cobra rotors almost instantly got the super-small cracks that slowly grew larger over 2-3 events before cracking.

I also think Marshall has about 10 events over the last 3-4 years on his "used" Stoptech rotors. He also has a 4-hour enduro and 6 1/2 hours (from the 8 hour enduro).
It is a large expense up front but I am completely sold on them.