OK I can guarantee if you are using a genuine Shindengen FH012AA or FH020AA they work on all three phase Ducati, I have not personally tried one with the early single phase generators, you are right to be cautious though as there are a lot of Chinese copy units floating about.
http://www.shindengen.co.uk/index.asp?page=aboutus
Shindengen - World leading manufacturer of energy conversion products such as rectifier diodes, schottky diodes, power MOSFETs, bridge diodes etc. they are Japanese with a European HQ in the UK beware of anything coming out of China