Hi Ted,

I find that when using the factory Composer Patterns I seldom use a voice in the left hand because there is just too much going on. This is especially true with many if the Big Band patterns. You may want to take a look back at the Swing file on the KN6000 page of www.kool-keys.com. Most of these arrangements were done to simulate an 18 piece band. Of course if you are arranging a song to sound like a small group it might be nice to have to have a small string section or some voices in the left hand. And, as Chuck suggests when playing traditional organ style the left hand could be used along with just a bass line for a B3 approach or a choir with a church organ.
In the end it might be a good idea to sequence a short part of the arrangement and carefully listen to your set up. Many times LESS turns out to be MORE.

Frank