Well, the Genovox is definitely a heavy piece, but remove the analog electronics, and its somewhere between 27-28 pounds. Same with some of the older Cordovox accordions that were 31-32 pounds... and 25 pounds when gutted. A big Bayan is an unchangeable weight that one is stuck with and cannot do a thing to change, unless you pull out some reed blocks... lol
I think Bayan by their very design have to be some of the heaviest designed accordions on the market, but there are specific reasons, that design results in very deep and loud tones and that cannot be achieved without size and weight.
In terms of non-Bayan, I think the 70's Hohner are pretty heavy. A Hohner Morino VI N Is factory rated at 16kg and the Artiste X N is known to be about 1kg heavier... both of these weights are without straps, so adding 2 pounds for straps is not unreasonable. That comes out to around 17kg (~37 pounds) and 18kg (near 40 pounds) each with a good pair of straps.
