The Port would be happy with .xps, .xpo, .sps and .spo files - they're all the same thing. However the PS2 that receives them won't be.
There are 4 lines of code that appear between all saved game files (I believe this includes replays, but I've never tried). They are different NTSC to PAL. These need to be changed in saved games before they will open on the PS2.
Other than that, everything's the same.