It would also be could if you could just adjust the amount of vintage to the various destinations independently, so set different amounts of variance for Pitch, Filter, Envelopes, independently, per patch.
Yeah, independently is ultimately the best approach, as certain sound designs benefit from different type of per-voice offsets. On instruments with a voices mod source, or key-step sequencer, you can dial in your own vintage offsets on a per-patch basis (I've done this extensively on Rev2, Polybrute, and Deepmind), and it gives you ultimate control over exactly how organic/vintage/loose each section of the synth is (oscillators, filter params, envelopes, lfos, etc)
For instruments like P5, P6, OB6 with simpler UIs and more modest mod capabilities, the Vintage Knob approach is a good option though. As mentioned earlier in this thread, I think the best possibility would be to just have a few different Vintage Knob offset tables that can be selected.
ie:
0. Slop Mode (original implementation),
1. Vintage Mode 1 (current vintage table of offsets)
2. Vintage Mode 2 (same as current vintage mode 1, but with Osc1 vs Osc2 separation offsets)
3. Vintage Mode 3 (high osc offsets like current in VM1 + separation, but lower filter cutoff / env ADR offsets)
4. Vintage Mode 4 (only osc offsets and filter cutoff freq offsets, no env ADR or LFO offsets)
5. Vintage Mode 5 (only envelope offsets and LFO rate, no osc or filter freq offsets)
I think that this approach of just having a few different tables of vintage offsets would be the easiest for Seq to implement, and give users the ability to get more control over vintage behavior, depending on whether you're creating a Pad, Strings, Stab, Lead, Bass, or other sound design which will benefit from different Vintage/Organic offset focus.
The tables of offsets are most likely just 2D arrays of integers that only take up a few kilobytes in firmware... so adding a few more offset lookup tables should require minimal resources..., and with the current OS menu, it would be easy to just have a few more options to select from, in the same way Vintage Mode is currently selected.