why? i personally race against a 10mm supercub all the time and it consistently gets beat by my 10mm cub and my brothers 4mm cub. its not all about cc's anyway. if that was the case then no one would bother build anything smaller than a 500cc motor, but we always see smaller motors beating on big ones.
im not sure what the cost difference is between the cub and supercub, but i cant see how it could be worth it.