I have been using E15 for over a year now. Offers virtually the same mpg as E10 in my vehicles, yet is typically priced 5 to 10 cents a gallon cheaper. When prices fluctuate seasonally, I change blends relative to the price spreads. I have used E10, E15, E20 E30, and E85 over the last several years. E85, the price spread hasn't justified its use in my area for a while.
While I have no issues with using ethanol in fuel, I will freely admit that a lot of this stuff is a quid pro quo between government and various interest groups. And not just some corn lobby thing. The greenie crowd and others have a vested interest also. And there is a lot of money that flows from K street to politician pockets over this issue. Both parties.