Yes, higher octane is more resistant to combustion. It is used for higher compression engines such as on sport bikes and sports cars, where more pre-detonation (pinging) can occur due to the higher compression of the fuel/air mixture taking place, which causes the hotter vapor to combust before the spark plug can ignite it. The higher octane helps stabilize this combustion to reduce pre-detonation.
So, it's not so much that the lower octane would be better for the lower compression engines, it's that the higher octane is not necessary and would provide no benefit.
One thing I noticed when trying higher octane on my bike a while back, was that in cold weather, the bike was harder to start using higher octane than with the lower octane.
As long your bike doesn't ping using the lower octane, the low octane should be perfectly fine.
Last edited by casilver; 05-04-2010 at 10:51 PM.