unless its a high HP machine that needs the extra octance to prevent pinging or such, i doubt that you will ever get any measurable performance/maintenaince/positive gains. For any std motor, regular 91 octance is fine (unless the manufactuer specifies oherwise). Hec for most mildly worked motors, 91 octane is fine.

Yes, in theory higher octane equals more power but its not that simple.

In saying that, for the extra few dolars per tank, the higher octane fuel isnt a bad investment really, just not measurable in any way... which doesent make it a good investment at all....