Hi Karl,
How heavy are your problems? I have saved different kind of midifiles and noticed that the files saved on the KN7000 where only a bit bigger than the originals to a maximum of 10%.
I haven't looked into it thoroughly, but my first assumption is that it might have to do with the midi format in which the files are saved. Using midi converters, you will see a difference in saving a midifile in midiformat 0 or 1. The same goes for the standard GM midiformat or the "extended" GM2 format. I didn't notice much difference in filesize saving from the KN7000 compared to software converters, while saving in GM2-mode and midiformat 0 what actually is the way the KN7000 saves midifiles.
If you want to save bits, you might consider saving in Technics mode, saving ONLY the sequencer part. In most cases the filesize was reduced to about 60% of the original.
Regards, Ad.