The rotors on the new Z and the Z51 C6 look like quality pieces. They have the same fit and finish as a brembo piece. I know a few delphi engineers that worked on the brake system for these cars and if there was a compromise, it would not have been put on the car.
I will let you know how they hold up in testing (IMG:
http://www.frrax.com/rrforum/style_emoticons/default/wink.gif)