The 21 also allows one to rearrange the bars to suit.... I did essentially an end-to-end flip, putting the C-G-F-Bb bars at the
'bottom' end and the A-D bars at the top. I also recut felt and made an E^maj out of a seldom used bar, and put that above the A. It let me both put the chords *I* use most closer to the center/sound hole and use a more comfortable (to me) fingering system.

*IF* you try any of that, plan carefully and label everything.