I'm not aware of any vendors going to E15 yet, due to consumer outcry. Most of the pumps around here are still labeled "up to 10%".
Curiously enough, when the Chevron up the road from me got new pumps, they never bothered to put those labels back. I don't see "up to 10% ethanol" anywhere in the station. I've thought about complaining to the state, but I don't know where to complain. (Charlie? Have you any insight?) I've usually got something else going on, anyway.
But... I don't feel like being charitable, and just "reminding" them, since they have another station a couple miles from here that sells 90 octane "no ethanol" gas for over $3 per gallon. Since they want to gouge, I wouldn't mind seeing them get fined for improper product labeling.
I haven't really experienced any bad thingsā¢, due to E10, other than what I perceive to be really crappy mileage, compared to what I'm supposed to be getting. (Of course, my driving style doesn't have a thing to do with it, I'm sure.)
My car is "flex fuel", and will adjust for anything up to E85, so even if I was feeding it a steady diet of E15, it shouldn't hurt anything.