I've been using ethanol for almost 20 years here in Iowa, both in new bikes and in my antique bikes and cars, never a problem.
What I most worried about, in my antiques, was the lack of lead for the valve guides. Turns out that lead additives were a marketing gimmic from the 60s (according to a book written by an investigator) I put 30 thousand plus miles on my 68 and 71 trumpet motors, no noticable valve train damage.
