So what are the major differences between the two. The new FX8 is supposed to be the newer sportier model?
I wathed the new video of the FX8 and did not see what the major difference to the SS.

Pretty much just paint and trim.

The FX8 also has the Ilmor Twin MV10 725 INDYŽ Stern Drive System as an option and the 400 SS does not.

Extra bling. As mentioned color,led lights, carbon fiber etc. A guy I know bought the first fx 8 with the ilmors and indy drives. Boat is a beautiful gun metal gray and everything including the arch is painted the same. It looks fast even standing stiill. Said he got 70 mph with 12 people on board and the genny running for the ac in a recent poker run. Bought it used from the original owner who took possesion and decided he wanted a true offshore instead. Paid 750 used(5hrs). Beautiful boat, but overpriced in my opinion. probally in the high 8's new.