I remember this thread came up some years back. The Doepfer Low Pass Gate will get you something but it does behave slightly differently from the discontinued Plan B Low Pass gate and some of the other ones out there. In "Both" mode you still get a dampened sound with the vactrol decay. I guess the thing is as far as I can tell is that some other LPGs have things tweaked to emphasize the decay much further and have a both mode that decays longer. One might think that an envelope tweaked differently would make the Doepfer sound closer but the effect is different. This would be because the sound is the LPG's behavior once the CV has closed it. That's different from CV-ing the release longer. So my conclusion would be you'll get that type of sound but a struggle to really nail a very specific sound.

As for other details, it is correct that you want a rich enough sound to hear the lowpass effect well and you usually send it want amounts to a trigger pulse, not even an envelope. The vactrol's short attack and long decay creates the envelope effect.

As for the wavefolder connection. IMHO that's another recreation attempt issue. The Buchla 259, perhaps the most expensive and one of the most legendary VCO out there as well as the Music Easel VCO and different sounding 261e use a wavefolder as a timbre shaper. Given that the Buchlas were making "Buchla" sounds years before it's release one can conclude that a wavefolder is part of a more specific recreation of say a 259 or a Music Easel.

nick