As I said in an earlier post, I've not yet found a vintage horn that 'lights my fire'.
Have you ever tried one that's
just been totally overhauled?
I had a 1973 Buffet Superdynaction a few years ago, some say a MkVI contender, not really vintage but played perfectly to my ears although I found, as Steve Howard did in his review of the alto, that it couldn't be pushed to any great volume. See:
Buffet Super Dynaction (SDA) alto saxophone review
I also went to look at an SBA a few years back but it did absolutely nothing for me, perhaps due to its playing condition?
Then some months ago I stumbled on a 1958 SDA, bought it for a song, had it totally overhauled, and it has great volume, which could be something to do with key heights (as Matt Stohrer explains below).
View: https://youtu.be/-EvpQBeK0NQ?t=439
So, as has been said by others here, a vintage horn could simply be out of regulation but we're predisposed to think more modern must mean better even when faced with all the hype about classic vintage horns being preferred and the MkVI still being seen as the greatest ever.
It's perhaps unfair to knock an older horn unless it's fresh out of a respected repair shop with brand new everything.
For the time being, until something else knocks it off its perch, my 1958 SDA is perfect and its ergonomics are simply superb compared to more modern key work.