OK I can say from personal experiance that Silkolene Pro 4 10W-40 Full sythentic kicks huge ass!!!!
I still cannot get over the difference it made to my SOTP Dyno and especially the transmission. After changing to the Silkolene the tranny felt like it had been to the gunsmith and had gotten smoothed and polished. It really made a difference. The engine didn't really quiet down much but it certainly "Seems" to run a little freer, a little stronger.
Silkolene Race products
It's a little pricey but I feel it's an excellent product and I'll prolly stick with it.
According to SportRider Mag, Amsoil is also a real good synthetic oil. You might want to avoid a synthetic with a really large concentration of Molly though. In theory the high molly content could lead to some clutch slippage.
In my opinion, full synthetic is the way to go, they don't break down anything like regular oils, they can take more abuse, and basically just work better. Synthetic blends I think are mostly just a price based compromise. Go full synthetic and gie your motor the best protection you can get.
The Oil test in Sport Rider mag, proved only one thing conclusively really, and that is that Synthetic Oils are far superior to traditional oils.