Very interesting posts in this thread but the majority of the information and data cited indicates that the spoiler, by itself, affects the aerodynamic characteristics of our FFHs in a very small way at best. The MPG benefit is so small that none of us would ever be able to measure it at the gas pump where it really matters. It would seem that for all practical purposes the spoiler is a styling component and a matter of personal taste.
I'm glad Ford makes it an option for those that like it and for those that don't you can purchase a FFH without it. Makes us all happy, right?