I have one verified problem with ethanol.
My lawn equipment. Echo Gas blower, the plug in the tank that the vent and fuel lines go through has disolved away from inside the tank. Entire bottom of this fitting has melted and is now residue on bottom of the tank. The only explanation is ethanol. Thing is not that old, possibley 5yr old or so.
I have other power equpment and have not noted the same issue yet. However they never get tank full and always stored with the tank in position that the fitting is always dry. Blower may get tipped over on garage floor or stored in odd position.