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Further to my post (above) he wears his shoulder straps very loose, his accordion hanging very low when he plays standing (centered about his belly button), so much for protocol regarding shoulder straps!

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Hi Dingo,
French made CBAs are deceptive. They are pretty compact, but tend to be a bit on the heavy side. I have a Maugein Mini Sonora that is about 3/4 size with 96 basses and it weighs 10.5 kg. Cavagnolo are now marketing boxes made from some "new tech" compound or other that's supposed to be lighter.
You mentioned "old style" CBA fingering. Even today, some players still tend to use it, although I dare say that it will die out in a generation or two, with the possible exception of some regional folk styles. As with any tradition old habits die hard, and the biggest part of the French musette repertoire was written on the presumption that players would not be making very much use of their right thumbs, if at all. It was in fact an urban "folk" style in its original form, and it was "lifted" from three row diatonic type accordions. It probably took 50 years before they realised that they weren't playing diatonic accordions, and the method books were finally revised in the early 70s, to include use of the thumb on the 1st and 2nd rows. Not on the 3rd row, as the standard French CBA has only 4 rows of treble buttons, and the method books only cater for those.
People like me now have to contend with an extra finger that usually makes things easier, but at the same time can cause problems that weren't there before. Some people, like Mr Cortes, have obviously decided it is better to stick with what they are most comfortable with.
With regard to strap etiquette, a fair number of older French and Belgian players played standing with the top of the accordion almost at waist level. If you have arms like a gorilla and a backbone like a poker then I suppose it doesn't really matter, but I'd rather sit and play mine as I have short arms and a backbone like a boomerang.
In the earlier days of musette it was all about image and vanity, and it wouldn't do to walk on stage with your accordion strapped on in the approved manner. You also needed the brightest jacket in the world, a toupee, or 10 bottles of black hair dye. If you ordered your accordion with a fancy button configuration you had gone that little bit further, and if you could play it whilst holding it above your head, so much the better. If you ever try playing walking around make sure your kids or grandkids haven't left any roller skates lying around, as I put one of my accordions through the side of a glass display cabinet after treading on an errant roller skate.