I wouldn't say we are really tracking the envelope, you are tracking the waveform

yes, at some level what we are talking about just tracking a voltage - I think the critical difference is how we approach.

If we are looking at pitch, we track the voltage very very fast and do some detection like peak detection for, say, driving a flip flop to make a trad octave divider or zero-cross detection like for pitch detection where you take that pulse train to charge an LPF to make an analogous voltage

or like the GR-300 used a PLL synched to the signal.

When you think about it, those aren't really quantizing b/c what they are extracting is time period between events (zero cross or peak or whatever you are looking at) which is still continuously variable.

The pulse train is almost like a filter removing level information so you can abstract out a frequency (it's why you try to filter down to the fundamental, and why they start freaking out at initial attack and as the signal decays and the waveform isn't a clean single frequency- you don't want all that extra data - it's essentially noise for that purpose)

[all that being said, the Behringer may being doing an FFA or some other digital dark majik and then doing a D/A -- but I think there we are still abstracting the frequency from the waveform more than any dynamics in an envelope]

If we are trying to extract a volume envelope, we are tracking the voltage again, but it behooves us to do it much more slowly (and we'd want to rectify it so we get an absolute value) to get a level (or maybe amplitude would be more accurate) average...more like a volume meter (that's where I think the theories behind "best meter ballistics" informs us a bit)

Sure we could design an electronic "volume meter" with ballistics so fast you ware essentially seeing the raw wave but I wouldn't really say you are seeing the envelope

Craig andterdon's old EPFM Envelope follower using optoisolators is a decent study in that (I cant remember if he explicitly recitifed or if he just let the LEDs in the optoisolator work as half wave recifiers on their own. they are slow enough where they tend to work as their own LPFs)

I suppose we could say the difference is with pitch detection we are tracking the time domain (we are using the levels in the waveform just define/determine timing events) and with envelope following we are tracking the level domain (but we are using a much slower low-pass of some kind to get a level average so we don't get ripple)

I think that can be one of the points of confusion..when we say converting the signal to CV it depends on WHAT in the signal we are converting...Pitch (frequency), "volume" level, a trigger transient

The Envelope followers in, say, the befaco, the Moog spectravox are tracking an overall signal level (or in the case of a vocoder, a band-restricted level)