Another potentially big difference is Avis status. The old CO card continues to give Avis President's Club (which is almost impossible to obtain otherwise, and can be a Big Deal if you rent cars a lot), whereas that benefit is going away from the new Club card. Frankly, this is a lot more meaningful to me than the 1.5x miles (I have other cards that get me 2x miles on most of my purchases).
Have we confirmed that this will be the case?