I have a spec stage 1 - just completing the break in period. I also installed a new stainless steel flywheel. I had a slight amount of chatter on the first day and that was about it. It grabs like a mofo like others have described. You need to match revs for it to be smooth, otherwise it will grab and jerk you around. I think that it typical of any performance clutch.
I called to check on the Timken bearing, as you may read about others trashing the "plastic" t/o bearing. I spoke to the spec guys and they confirmed it was a Timken bearing that they have been using for about a year with good results. Just to verify I went into a parts store and looked at a Timken bearing and sure enough it is the exact same (about $35). They will swap it out for an all steel bearing if you prefer. I would stick with the TImken though, as it appears to have the best reputation.
The price seems fair.
Howard