every time I have tried to run higher octane gas in my F150 I hear pinging, which seems counter intuitive based on the science of it all.
It could be that you're getting incomplete ignition, then the computer tries to tell the engine to compensate, still within norms enough to not throw a code, but changes something and causes it.
You're right, though, it's counter-intuitive to the norm.
More than anything, I've only ever noticed a slight reduction in mileage due to lack of complete combustion of higher-octane fuels in my cars that don't need it.