Something else I do:

Since I use a laptop for MP3s, and the on board sequencer in my kb - I have a need to scroll through choices during arranger play,as I decide on the next number. I like having the option of switching my chord trigger hand from left to right on the fly so I can scroll with the opposite hand....whichever is more comfortable.

This is especially important if I'm using the vocal harmonizer, so I can continue to trigger the correct chords as I fumble with directories.