This topic has been discussed a lot here. You'll get differing opinions based on what works best for the folks who respond. There are a lot of us who believe that using high octane fuel will only benefit the gas station owners and the oil company.
Unless you're running very high compression there is no need to spend the extra money on high octane gasoline. Your little engine won''t know or care.
Here's some reading for you. Just type in 'high octane' in the search box > http://www.google.com/cse?cx=partner...ane&gsc.page=1