Moinmoin,
I seem to read the word "vintage" to often...
By its very nature every single synthesizer is an instrument allowing a multitude of different sounds. What may "vintage" mean under this condition?
Being nearly 60 years of age and making music in bands for 40+ years I do own some instruments, most of them "vintage".
I very appreciate the P'08's (my latest acquisition concerning keyboards) facility to stay in tune, enabling me to play chords after 2 hours on stage or even more time during rehearsals without painful retuning. My monophonic synthesizer from the late 70s may be very "vintage" but does not even allow me to play long single notes in tune with the band without regular retuning. And yes, it is equipped with thermal biasing resistors in its exponentiator circuits.
I remember an interview with John Medeski when he was asked to tell the difference between a "real Hammond" and contemporary digital clones. He told that no normal listener, even no musician would be able to hear the difference in sound on CD. The musician however would experience a big difference when playing it, which of course will make him play different, which may well be heared.
This statement opened my mind. For me "vintage subtractive synthesizer" means a user interface allowing me to tweek all the classical parameters of such an animal. I do not want to search my way through menues and screens, handle mice, computer keypads or touchscreens. i need instant reaction, which analog circuitry certainly delivers.
Another reason is non-linearity: Analog circuits behave more or less "funny" when driven to or pushed above their limits (of linearity). This BTW is where my 70s monophonic really shines.
And let's be true: As with "vintage" guitars of the same make and model, "vintage" Minimoogs, Odysseys, P5, ... do not sound all the same.
Another one: The main difference between Jan Hammer (Moog) and George Duke (Arp) does not lie in their tools.
I respect Sacred Synthesis' opinion, leading him to compare and judge "virgin" sawtooth sounds. For me however the overall sound, which is not only but to the same extent charctarized by filters, is of more importance, and here again at the limits: As with guitarists and horn players the most interesting sounds are at the border to catastrophe. In my opinion this is the main reason for the necessity of instant parameter tweaking. It will be too late when it already howls or blows the tweeters...
I will welcome any instrument allowing this, may it be "vintage" or modern, even "digital". At the moment however, my personal borders of creativity do not lie in my instruments, but in myself. So back to practicing...
Just my opinion, Your mileage may vary of course.
Martin