A couple videos of #13 with the extra base buttons and extra mid row of reeds. Bb. Takes some getting used to, but I can see where it'd be handy. J'etais au bal I tried to modulate from F to Eb using the Eb base/chord, and Eunice Waltz I tried to switch to the Eb chords. Switching buttons mid song and back is harder than I anticipated.
The extra mid row of reeds uses noticeably more air, but really about the same as playing a 9 button.
SWEET! I love the sound of the Binci reeds. That four bass setup has a lot of potential. It may even be the future of Cajun accordions. If I ever can afford a handmade box, I will definitely contact you. I really like that four bass setup.