I know the CF shafts we used on the Skyline GT-R R34's and Syclone awd turbo trucks were a great addition to the effort of removing weight in the driveline.
And we didn't have ANY failures with vehichles all the way up to 1200 hp and constant track use.
If something else comes into play...off track excursion etc....then you have other probs as well.
Go for the group buy. In fact ...you should buy Chris's shaft (from previous posted link) >
(
http://www.zpost.com/forums/showthread.php?t=513719) ...and get the ball rolling.