60,000 miles of hard driving and autocross on my LuK SVT clutch that I bought from Team Ford about 5 years ago. No issues.
My understanding was that the LuK clutches you buy today from aftermarket retailers are just equivalent to the regular non-SVT Duratec clutches, and there's no differentiation anymore. The only place you can get an honest-to-God SVT OEM clutch is from Ford - who doesn't carry them anymore. That said, it would probably be a good idea to call around (maybe have Steve at Tasca research it for you, and see if he can find any).
Also, Brian, maybe you can answer this. Are the SVT and non-SVT clutch discs different in any way? Is the friction surface of the disc different, or the hub springs? Or is the difference between the two only lie in the pressure plate?