Neil,
Nichols have probably been making performance flywheels the longest. In fact, a lot of manufacturers (including Ducati) now try to copy Nichols' products and innovations. For example, Ducati copied Nichols' engine mount bolts (which Nichols started to make in '93), and then in '97 Ducati tried to copy his aluminium flywheels (which Nichols has made since '95), and now Ducati has begun offering dual spark-plug heads that Nichols has done for over eight years. I think that it shows that Ducati has verified that the guys at Nichols know what they're doing.
In any case, anyone who is not yet familiar with Nichols' performance parts is in for a pleasant surprise.
Also, whose flywheel has a money-back guarantee?
Ducati Performance - no
STM - nope
A lighten stock unit - nada
Nichols - yes
check them out on
http://www.nicholsmfg.com