In my experience with 2-strokes there are two mods that demand octane: higher compression and ignition advance. In fact, these mods are why most modern cars require higher octane but I digress...... The goal of higher octane fuel is to prevent "detonation". I'm sure that detonation is discussed in more scientific terms that I can manage this early in the morning but the result of detonation is that your piston errodes. Typically the crown becomes curved at the edges but however the damage occurs this errossion causes a loss in compression and performance. If you're unlucky you can get cylinder damage from big chunks of piston coming off and I suppose a catastrophic piston failure is possible (although I think this would have to be acompanied by a lean condition). Whew, this is getting long winded!
If you stay stock with your bike there is no need
for higher octane. If you change compression or ignition advance you most certainly should run a higher octane.
Personally I run premium pump fuel.....even though I conceed it isn't necessary. I'm so accustomed to running higher octane than necessary that I no longer think of it as an extra expense.
My last advice is to use a fuel stabilizer if you are not running a tank of fuel through the system every month. As much as I ride my scooter I only fill up about every two months.