I know that this subject has been discussed to death from hearsay. So for actual evidence, on my Rhino, I have 9:1 compression, or I compress my fuel mixture down 9 times. At stock ignition advance, and normal use, I am fine using 87 octane fuel. My Dynatek advances the ignition +4° and causes pinging (detonation) under load. It has also been documented that Rhinos crack the upper case behind the top of the cylinder from this'd detonation. 91 octane fuel helps to eleviate this issue.
Wolverine engines are 10:1 compression, or compress the fuel 10 times smaller. Fortunately the pcv is turntable and I can tune down the ignition map for cheaper fuel, at the lose of some efficiency, power and throttle response. Your welcome to run whichever fuel, I spend the extra 30 cents per gallon for my premium fuel.