Anglo/English
When I wrote the last post I was also thinking about the difficulty piano accordion players have getting the bounce into dance tunes that a melodeon player seems get easily. Again it is surely to do with the 'limitations' of the push/pull instrument. Particularly in cajun playing there is a characteristic lurch which comes from cross keying (playing a G melodeon in D for example) which naturally imbues cajun two steps with an off beat emphasis. By contrast it is difficult to get a melodeon to sound fluid without a lot of practice.
So maybe the same argument about the difference between fiddle and violin can be applied 'push/pull' versus 'same note' free reed instruments. In both cases the limitations of the instrument and playing method are converted into virtues which suit the purpose. Just a thought ;)