Yeah there is ethanol in "normal" gasoline, but at 10% its really not going to affect anything. With 85% ethanol you can run into problems on the fuel system. From what I have heard, cannot confirm it though, it tears apart normal injectors so they use stainless.
I can't see it having improved performance on a stock motor. Less BTU's and higher octane. Using higher octane then what the motor is designed for will burn slower and cooler, then the right octane.
To make up for these loses you would want to raise the compression and/or, like Bigchelis stated, advance the timing alot.
Sorry if it seemed like I was ranting or offending anyone, it was not meant in that way at all. I just absolutely hate the idea of ethanol as an alternative fuel.
So sorry once again if I offended anyone.