The FMX is almost bullet proof. It is one of the best automatics Ford ever made. How do I know? I would starve to death if I sold only FMX parts since I have seldom sold more than ONE FMX part in any year of the last 30 years. C4 parts put food on my table day after day, month after month, and year after year.
It is heavy, for sure, about 40 pounds heavier than a C6. But it has less parasitic drag than either the C4 or the C6, so you get more horses to the wheels.