[BrianG]

Kinda depends on the voltage you want to use too. MM handles up to 3s, some can do 4s or even 5s on earlier models, but need a BEC on anything 3s and up. The MMPro has the sensored option, switching BEC, and about the same current handling, but takes up to 6s. 6s@80A > 3s@100A (that's assuming those current ratings are accurate).

Also remember that the MMPro uses better FETs than the older MM, so even though it may have fewer of them, both ESCs have about the same current rating overall.