[grumpyunk]

If you want ethanol-free fuel, you can buy it that way, or make your E10 free by adding water. The ethanol mixed with gasoline can be forced to precipitate out of the mixture by adding water. You can watch it being done on youtube if you want.
The fuel in a video was placed into a glass(?) jug, and a measured amount of water added. Within a short while, the ethanol started to fall out of solution, and gather at the bottom. This example waited some time, an hour or more, and then decanted the ethanol-free fuel into his gas can. I do not remember the proportion or amount of water needed for each gallon.
You can also calculate the Exx ratio in your fuel using calibrated glassware. I don't remeber the name, but you add specific amount of water to a specific amount of fuel and then wait. The level(amount) at the bottom of the tube tells the percentage ethanol in the fuel.
Premium, high-octane, fuel just prevents or slows the combustion of fuel due to higher compression pressure. The flame front starts as the spark plug rather than than having more than one ignition point inside the combustion chamber. The single flame will burn smoothly while two flame fronts colliding will cause ping/knock/pre-ignition. Premium fuel actually burns slower than regular. From what I understand.
Using premium fuel provides no performance advantage unless the engine is designed to use it. These engines should tolerate ethanol fuel, they may not, as it has been on the market for quite some time and they don't like to pay for repairs caused by its use. Keep the fuel fresh, drain as needed, and adding some MMO or 2T lube to a tank of gas won't hurt anything, and may prevent rust on the inside of the tank and corrosion of the float bowl & associated parts.
IMO
tom