I have the old carbon/kevlar stage III and 643rwhp. It seems to be holding just fine. I dont do hole shots but hammer it from 40 rolls and it grabs just fine. Not sure about longevity though. The clutch has a total of about 3k miles on it. Only about 600 miles of 643rwhp and 2400 miles of 568 rwhp.
Just my experience. FYI...I'm watching for peoples experience with the Aussie clutch.