So, did we ever get a definitive answer on this? My 1000 mile service is looming, at which time the Syn 3 will be replaced by Amsoil & Redline; I have always used the standard three - Amsoil in the motor, MTL in the primary, and Shockproof Heavy in the trans. I'm about to buy for the service, so got to wondering if the V-Twin flavours have any advantage over the normal ones (disregarding any price difference...) 
Jim
Never use Syn 3 in your scoot.....PLEASE

With the other oils, Mobile 1..Amsoil..Redline......they are all good. I have not seen any proof that one is better than the other. None of them have had any less problems than the others. If you have a bad bearing, any oil is not going to stop the inevitable.
If you are changing your own oil, choose the one that is easiest to purchase for you......IMHO