While it's getting a little OT i'll add my experiences with octane and ethanol:

Ethanol is ok apart from the fact that it tends to harden the fuel pump diaphragm in the carb. However, if you replace it with the teflon (brownish colour) item in a walbro gasket kit, you should not have any problems.

In my part of the world, the higher octane fuels are not JUST higher octane, they also have a higher energy rating meaning higher octane for me IS worth it. I see a significant improvement in power when using premium fuel.

Stick to getting your fuel fresh from a station that has high turnover. Fuel is not meant to last more than a month or so and most of the 'volatiles' evaporate off quickly. For my (rc) boat, i only buy,mix and use on the day. I do not store fuel at all anymore. Once I had some old fuel but unmixed in a sealed container for 2 months. When i used that, the boat would just not run right - fresh fuel and it was back up to pace.