Interesting discussion on octane ratings here
Personally I've been using simply the minimum recommended octane (93 RON here). My thinking was I'd just pay what's needed to give it the gas it'll run on, and that higher octane isn't really worth it unless I drove some sort of high-compression or turbo monster.
Ran the same octane on trackdays and I didn't have any issues...although maybe I should try the higher octane from time to time.