[longhornchris04]

Brand is about the additives
Location is about the "freshness" - i.e. how long its been sitting and the propensity to have water / other crap in the tank
Octane is about... well we all know what octane is about.

Also, at least to my knowledge, running higher octane in an air-cooled motor adds a measure of safety in the event your heads overtemp. Not that you want to risk the engine letting it overheat, but overheating alone is better than overheating + spark knock. Additionally, with the less sophisticated fuel systems (i.e. Carbs or CIS), it helps protect the engine if your fuel system is running lean. This is technically an issue with Mototronic and later EFI - but modern sensors and emissions controls have lessened the effect greatly.

One word of caution about separating out the ethanol -- ethanol is often used as an octane booster... remove it and the fuel's octane rating will go down.