Interesting. I play pianokeys too and later regretted that because buttonaccordions made things possible that are hardly possible with pianokeys. I could very well hear the difference in playing because we had two great accordionplayers in my country, Harry Mooten, who played on pianokeys, and Johnny Meyer, who played buttonaccordion. I was jealous of what Johnny Meyer could do. Besides it is very easy to change keys on a buttonaccordion.
It seems Leon Sash had a workaround for that problem. Great to hear this.