you're exactly right. higher octane burns SLOWER, thus preventing hot combustion chamber tempatures from igniting the gasoline BEFORE the sparkplug sparks (this is called detonation). with detonation, you've got rapidly expanding gases in two or more chambers that are on opposite sides of the crank. something has to give, and it's probably going to be a rod or a piston/piston ring. anyone that's run a turbo engine knows this, and that's why most turbos run 93 octane (or higher), because of the higher charge tempatures of the air mixing with the gas. most modern sport bikes have very high compressions which causes the air to become hot (higher pressure = hotter, lower pressure = cooler). so many sport bikes (like mine) suggest 93 octane to prevent problems with detonation.

so if your bike manufacturer recommends a specific octane, NEVER go below it.

and another common misconception, lower octane fuel actually can create more horsepower due to it's quicker combustion. that's why the rider mentioned uses a lower octane on the drag strip. but if you can control the charge tempatures and have things tuned to prevent detonation, it's not a bad idea.