As an ex-piano accordion player who switched to melodeon I know exactly why he'd switch. I went though a phase of B/C/C# chromatic button accordion on the way, but in the end it was power-to-weight ratio that got me on to the Hohner pokerwork, and then the Oakwood that I now play.

And those 4-stop 1-rows - there's nothing else that sounds like them.
[please refrain from obvious retorts....]

Dan Quinn used to play PA too. Not many people know that. It must have been a long time ago.

Anahata