While composers have a prefered voicing they can choose when composing a piece of music, I've received feedback from many educators that it's actually the student who is reading the music who has preferences on what the voicing should be for a measure or for all measures of music.

Therefore, I'd like to propose that it's the reader (student, consumer) of the music who should be able to easily and quickly change the voicing for a measure or piece of music from the practice/playback screen.