i have covered 30,000 hard miles on my Monster 6 380mm Hi specs and never had a problem
The longivity will depend on the pads used (DS2500 is my recommendation).
I have sold loads of kits and everyone has given positive feedback on them.
I have done Nurburg 6 times on them (84 laps) along with brands etc etc, and never had an issue with brake fade. I am on my 1st set of rotors, and 2nd set of pads.
Goodridge lines allround.
Highly recommended. 10% off through me too.