I have a Casio WK1800 (sorry I know nothing of an instrument definition thing for a wk1300) anyways. I really didn't have much moeny at all but was really enthusiastic about getting into MIDI sequencing. I bought my wk1800 for 400 bucks and have been very pleased with it's functionality. I great training tool as well for someone learning the ropes about MIDI.
As Tommyde pointed out you can not write SMF to the hard drive but... If you have PC ( I do) and a sequencer on it, you can easily playback the stored sequence in the Casio to record it on the PC's sequencer. It took me awhile to get this right. I finally found out about setting your recording sequencer to external MIDI clock mode... What a break through that was for me!!! Yay!!

I really like the ease of use this GM box is and it's really helpful in laying down drum tracks to my PC's sequencer.

I haven't gigged yet and am planning my first gig this october. I may not use it. I also recently purchased a FATAR sl880 which allows me to express myself and use the casio's sounds. I have a Yamaha MU90R on the way. I really hoping the piano will be usable!!

Anyway, I really dig my Casio WK1800 and recommend it as a great and easy GM tool for the home studio!

RW