I work in the marine engine trade. (western U.S.) Ethanol has been a boon to the gasoline engine repair and maritime rescue business. It is estimated by marine trade originations that gasoline and ethanol mixed fuels currently cause about 70-85% of engine failures. Not really a type of additional work we want.These engines (and outboards) and fuel tanks were never designed for this fuel. Unlike modern autos, marine fuel tanks are vented and absorb moisture rich air. Water related corrosion adds to the alcohol damage. I do not think anyone has worked out just the cost in lives lost at sea, lost boats, and the damage to the marine trades has resulted from this fuel. We only get to work on the boats that made it back.
Numeric stability is probably not all that important when you're guessing.