There are many opinions regarding petrol.
A good advise is to search "the net" as you can find test that have been conducted from 100% ethanol to 100% gasoline. The differences regarding efficiency or metal wear in cylinders are very close.
Regarding higher octane petrol it is for sure only a better ability to damping knocks with the ignition in the cylinders.
I would say the main reason for driving with high octane fuel is that you have less ethanol with it.
I use E5 petrol if possible instead of E10. As ethanol attracts water it therefore is corrosive to metal and aggressive to plastic and rubber.
Regards PerS