Guys I fitted the Aluminium SMFW today with my HPF Clutch which looked in good condition when it came out.
The chatter wasn't too bad for the limited miles that I've done. Unfortunately there is a grating noise and vibration in 800-1700rpm in 2nd and 3rd which I've read in 3 other threads written by SMFW'd 335i owners.
So guys go for the Steel SMFW if you get the chance as I heard this avoids these issues. Didn't get a chance to feel the difference in how it revs as I was too pissed off with the vibrating. I thought I had f'd up the install but a quick search shows someone on here with the same issue:
http://www.e90post.com/forums/showthread.php?t=487514
However, the Spec clutches are sprung so maybe these issues aren't present. Anyway I'm probably going to change to a Spec Stage 3+ in the future.