Amsoil and Mobile 1 are NOT the only synthetics that start with sythetic bases. I spoke with a number of companies at SEMA and they are closing the gap or surpassing those who started this trend.
An email to me from Royal Purple Engineering: "Royal Purple combines the highest quality synthetic base oils with its synthetic, proprietary SYNERLEC additive technology. Amsoil and Mobil 1 both start out with the same base oils as we do, these base oils are call PAO's (polyalphaolephins). The additive packages make the difference."