I am fancying with that idea myself since a while now. I didn't realize Stanley Clarke already went that route - interesting!
As Mica and Dave already said, you'll get 2 Direct Outputs and the crossovers, features I am truly missing on my current F-2B. On the other hand you'd pay twice the money for two F-1X compared to one F-2B.
Just one thing made me curious: When I ordered my Alembic bass I had been consulted by a very experienced long time Alembic user/owner and good friend of the Wickershams. To my surprise (and even Mica's), he said the sound of the F-2B was superior to the sound of the F-1X. He had them all in his life and he would always stick to the F-2B for that reason. We never never found out though, what technical difference would cause such difference in sound. Maybe it is just audible to his discriminating ears?
Today I wouldn't hesitate to try the F-1X, just because I'd like to have the mentioned features.
Hartmut