I've never had a problem with E10 in my EFI vehicles. That's not the case in my carburetor equipped vehicles. I also get significantly better milage when on Pemex gas compared to US gas.
The real problem I have with ethanol as a fuel additive is this:
The US and the world currently have a plentiful supply of crude oil reserves.
The world also has a significant number of starving and underfed people.
Our government mandates we use food crops to produce fuel thereby reducing the available food supply and driving up the price of the worlds remaining food supply.
What's wrong with this picture?
I'm no bleeding heart liberal, far from it. Rather it's my conservative bent that blames the government mandates for the high corn and food prices (and crappy fuel).
PS, I'm not naive enough to think that getting rid of the ethanol mandate would solve the world's food crisis. But it certainly wouldn't make it worse.