Originally Posted by inhiyu66
Am I wrong?
Of course you are.
1. The OP will use an U.S. address, so he'll get an annual 20% off voucher and can use the miles at a more convenient redemption rate. For example, an annual transatlantic roundtrip in C will cost him 72,000 miles (80,000 with MP).
2. The OP can also use his miles for companion awards. Here, a transatlantic C award for 2 will cost him 135,000 miles (160,000 with MP)
3. The reason behind using two programs is not to earn/burn the miles in the most ineffective way offered by each program (as the example used in your post strangely suggests), but in the most effective way! On the earning side, this means that you can benefit from special promotions regularly offered by both MP and M&M for flying on their respective metal. This will allow you to earn more miles than the official rates would suggest. And not to forget non-flying promos such as Ameniti and iDine on MP, or newspaper subscriptions on M&M.