How nice would high octane gas be?

Other that it being less efficient? Or massive tax dollars wasted on farming subsidies for ethanol? Not in vehicles, although I have not had a carbeurated car/bike since they forced the switch.

That said....it doesn't last as long in storage, and anything carbureted specifically marine, it causes nothing but havoc.

From what i've found out 10% is fine and don't know anybody who use it that have had problems.
what problems does it cause in carbureted engines?