If one runs more octane than needed, performance goes down and emissions go up.
If one has to up the octane to accomodate more static timing advance, then IMHO one should remove some timing rather than upping the octane. The gains are often simply not worth it when talking about the small octane increments found in pump gas.
Also, one can lose power before the onset of detonation - just another reason to not run on the ragged edge of pinging.
Good luck.