If you use the FS7 with the XDCA-FS7 it gives you a RAW output over SDI which lets you record 4096×2160 12-bit RAW on, for example, the Odyssey 7Q as (I think) Cinema DNG. If you’re happy with the 422/420 options (there’ll be 4K 422 intraframe coming in the next firmware) then you don’t need it.