I have heard a few good arguments that most small two stroke engines aren't designed to very high specifications and physically can't take advantage of higher octane fuel. I have used different octanes in multiple engines and consistently not noticed any difference.
What I have noticed is fuel from different companies perform differently (I acquired a good/bad station list when I first started driving.)
Speedway consistantly sucks (but their diesel seems okay)
Amoco/BP is good
Shell has always treated the car really well.
Sunoco is always good too (plus they've got lot-o-options on the octane levels)
Marathon has teetered on the fence.
I do practice using, exclusively, either high end or low end though, in hopes of getting fresher fuel. The middle isn't used as often I think (given the stations location) and I've heard it is common practice to mix the 87 with the middle tank (generally 89) if the station mis-estimated how much fuel they would need and ran out of tank space.
That being said I feel better sometimes getting the fancy fuel and even though I know it may not matter at all, I like to be happy, and I like my engine to be happy. Then we ride off into fields of blueberries and stuff outselves silly till we fall asleep in eachothers arms.