Turns out the cheapo AliExpress CGA card I've been using till now was pretty accurate, it has all the same bugs/snow etc. I suppose it's not too surprising, it has the same 6845 chip and that's sort of the most crucial component.
@rasteri it is kinda amazing to see there is still so much legacy industrial hardware left that it's affordable to manufacture new CGA cards (and how cost effective they are now thanks to CPLDs)
rasteri
polprog68k
steeph 
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