What are the advantages/disadvantages of a full keyboard w/ sounds n' whatnot against a midi controller and a rack version keyboard?

For example, why should I or should I not get a Fantom X8 rather than a Fantom XR and a CME VX8?

I'm a novice, so the only difference I can spot would be the $700 price difference.

Oh, and I don't know if a CME VX8 is any good, it just looks like it has all the knobs and whatnot I could need. If anyone knows any good midi controllers that have a good set of functions and 88 fully weighted keys (as realistic action as possible is best... I'm an intermediate pianist, so that's important), do let me know.