Fuji's FinalProof only utilizes the CMYK gamut.
Kodak's approval can reproduce a limited number of spot colors using its "Recipe Colors".
Wrong. The FinalProof has 10 donors it can utilize to simulate spot colors. Cyan, Magenta, Yellow, Black, Blue, Green, Red, Orange, White, and Silver. I have found my FinalProof to do as good of a job if not better than my Epson 9900. The ability to produce proofs of metallic spot colors is a huge advantage. The ability to proof directly on substrate (including metallic foiled paper) is a huge advantage. The big drawback is the cost of the films, the machine, the limited output size (21" x 25" - larger items must be tiled) and the space and time it requires for operation. There is only one application to feed the FinalProof with it's proprietary PD Pro application. I have been told that the FinalProof is no longer being manufactured and that the software is no longer being developed but that Fuji intends to keep consumables available for a long time. A good RIP that outputs a compatible TIFF is also a must - I use ORIS.
The Epson 9900 has 11 ink channels Cyan, Light Cyan, Magenta, Light Magenta, Yellow, Green, Orange, Photo Black, Light Black, Light Light Black, and Matte Black. The proofer is excellent but really only as good as the RIP you feed it with and the paper you put into it. I use ORIS but GMG and EFI also have excellent solutions.
I also get proofs produced by Kodak Approval from various prepress houses and customers. The proofs are also excellent.