His engine is thirteen years old. Even if it runs well, it's been around a long time. The RV8 likes to complain when not used properly, and the RV8 complains with carbon.
His coils may be original, or may have been replaced some time ago. If he's running factory replacement plug wires, it adds to the problem. Either way, his ignition system likely isn't at the top of it's game.
Now, consider this:
Platinum is the least conductive center electrode material available in spark plugs today. So, given the gap choices he mentioned, which makes more sense?
Cheers,
Kennith