I have a decent collection of early pressings of albums from the 1960’s to the 80’s and would estimate less than 1% are warped. But I have also come across very few 180 gram that are warped.
As far as sound quality I believe most of my older pressings sound either superior or equally as good as replacements I have purchased thar are 180 gram. I will say that there are a number of remasters on 180 gram that do sound fantastic.
sound quality has a lot to do with who the mastering engineer was and who cut the laquers and plates and where the albums are pressed.
i agree with the statement that I have come across many more new pressings with ticks regardless of LP weight than I have on the older pre 1990 pressings.