The Milodon rotor design is more prone to cavitation than the stock design. The Milodon pump is also more prone to drainback (without a doubt there will be posters who've never had that problem!).

The billet Milodon cover solves the gasket problem but other than pretty and "billet", what are you getting for $250 that the Muscle Motors cover doesn't give you for $100 ?!?!?