I think it's important to draw a line or two here... One would be, concensus seems to be that the lighter the flywheel, the more clatter there is, regardless of mfg. The second would be, there were some cheap flywheels running around (Eurospec) that quality was in question, were missing TDC marks and generally didn't perform well in terms of chatter/judder and clatter. Most, if not all, suppliers here caught on to that pretty quick and don't offer those SMF's any more. SBC clutches are quite popular and most people like them. I don't know who's flywheel they supply in their 'kit' but, by in large, it seems to work. Whether or not there are multiple flywheel mfg's to avoid I can't say directly. The only 'bad egg' that keeps coming up again and again is Eurospec. I don't think SBC uses them.