Phil,
Some accordions, as I understand it, are able to play an approximation of musette. It is not a "true" musette, but something approaching it.
Other accordions are musette tuned at the factory, which sort of implies that a "normal" double octave doesn't produce a true musette sound.
Something like a Sonola 5 voice "Festival" with 13 key changers can do the lot, being capable of both musette & double octave.
My take on this is that, if you want to play Parisian Café Music and Jazz, you probably need two instruments.
I play a bit of Edith Piaf myself, but can really only get fairly close to musette. It is not ideal, and I will eventually buy a proper musette tuned instrument.
Unlike many on this forum, I quite like Chinese instruments. You can listen to the 96 Bass Musette Chanson on The Accordion Shop website, and it doesn't sound too ghastly. Where else are you going to get a 96 Bass instrument, with a 3 year guarantee, for under £400, delivered???
My own Chanson is getting on a bit, but still works perfectly well.
Kind Regards,
Stephen.