I can certainly testify that it is no friend to carburettor floats. Had to replace both on my BMW R100RS and research strongly indicates that absorption of ethanol, or possibly one of the other aromatics in modern fuel, is the culprit. Thankfully my 45 has a brass float, but should it fail I will be replacing it with the aftermarket "rubber ducky" type which is said to be ethanol proof.
Bloody hell. Turbulent times ahead. Bet this time next year, they'll be many tales of woe....
To be fair, "ordinary" E5 does the same, but presumably over a longer period