Single-finger mode is intended primarily for non-keyboard players who want to make music with an arranger. However, it can be useful for advanced keyboardists (who might want to simplify some fingerings). Also, it can be useful for controllers other than keyboards. Fran mentions guitar. I have a Yamaha WX-5 wind controller that I would like to use with arranger functions. My idea would be to use a Roland PK-5 foot pedal to trigger chords. It would be helpful to have a scale function so that two feet would not be required to play minor chords.