I did some Roland rhythm conversions, with a 1800 user. She used the 1800 to convert the Roland files to Casio 1800 format (part of the 1800's 'built in' features. I then used the Casio Data Management software the finish the conversion, to the wk3000 format (this was in the rhythm converter section..cpt files converted to ckf...this is one of the options)

With the Casio Data Management software, you can actually do lots better rhythm constructions...even using midi files to make new rhythms. Once you get the feel of the 'how to' of the Casio software, you wouldn't want to mess with the 1800 (IMO)