Is there a list that lists down if a particular saxophone is a copy or based-off another saxophone? E.g. I just read Mr Howard's G4M vintage alto review, and it seems to be based off a Yanagisawa 992, and here it is mentioned the several AW sopranos are copies of yanagisawa sopranos.
there is not such a list and it would be impossible to compile one.
Part of the impossibility is that it is very difficult to know for sure that a horn is an exact copy because it might LOOK like an exact copy but how would you measure that the horn has precisely the same internal dimensions of the original horn it supposedly copies?
Another problem would be to have the pulse of all the immense amount of brands on the market. Only in Holland I have more than 30 at the moment and of course although some are made in the same factory of some others how would I know that? Besides there is nothing preventing any of these " brands" to source their saxophones next year elsewhere.
Also, most Chinese and Taiwanese " copies" tent to borrow most of the keywork from a certain model from a certain brand but you could easily find that some small detail has been taken from another saxophone from a different brand. So you end up with a saxophone based on a Selmer bodytube, with rolled toneholes applied on, Keilwerth style and Yanagisawa keywork.
There's also the subjectivity... e.g. C is a copy of B which is a copy of A.
Is C a copy of B or A? Logically and at design time it's a copy of B, but many would say it's a copy of A, not knowing about the B in between. And without inside knowledge it will be hard to tell, unless there was an extra feature in B which made it into C AND you're aware of the existence/details of B....