I know this is not speaking of a bike engine, but I had a buddy that purchased a brand new truck in 99. He went through the break in period and immedietly went to ams oil, in engine and trans and a synthetic gear lube in the rear and transfer case. He changed the oil every 7500 miles and trans fluid with filter every 20K. He just sold the truck back to the dealership he bought the truck from in 99, with 589K miles on it. The truck was a Chevrolet 1500 Z71 gasser. I am 100% convinced on Ams oil, and synthetic oils. Our engines rev at such a high RPM, the syn is the only way to go. A blend is cutting the lube qualities in half, and a conventional... well thats old school if you ask me.
I am also a fan of Marvel Mystery oil, I have personally seen this stuff do miracles to corroded and rusted engines, and do like the Lucas products. But if you take care of your engine right from the get go, use quality lubricating products, you should not have any problems with your stuff.