ROM from K2500 into K2500R

[ImaX]

Do you know if the K2500 rack-version uses the same expansions as the keyboard-version?

I have a fully loaded K2500XS - I just spent some thought about getting the rack-version and use it with my A90, so I wouldn't have to carry the big beast around with me. Perhaps I could use all expansions I already have in the keyboard-version with the rack...?

[Enigma™]

Yup - the ROM daughterboard that the chips plug into as well as the actual motherboard itself are very similar from rack to keyboard. KDFX is the same as well but I don't think the sampling is.
So to answer, yes you can have the roms from the 2500R to the 2500XS and vice-versa.