when I did Meta Morph for the Eigenharps, I also noticed that I could hear ‘zipper’ noise in some cases… (it was quite contextual in my case)
In the case of the Eigenharps, I’ve got a direct usb access to the hi-res data, and was sampling at sample rate - so could rule out ‘midi oddities’ (e.g. core midi / vcv midi handling).
I think its simply that when you use “midi” synth they all have a certain amount of slew to handle the midi steps, its primitive so never really exposed to the user -though, some allow control over this.
I found when writing my own ‘synths’ (c++ dsp), I had to do the same to make it usable esp. with expressive controllers, as they are modulating x/y/z so quickly, to the point you could consider it ‘noise’ (or chaos if you prefer ;))
and , vcv ( * ) and cv is like this, its often assumed to be continuous (at sample rate), with obvious exceptions ( v/oct , gates, trigs etc) , so few modules have slew (unlike midi), unless you add it yourself.
It’s an interesting area for expressive controllers, as when I added slew to the eigenharps I could instantly feel it (as ‘lag’) even when it was pretty subtle/fast, and if you do it too fast, it loses its effectiveness - so its a compromise/balance.
all that said… I also think its like pixel peeking (by photographers),
once you hear it, and start coding against it - I found I was became a bit hypersensitive to it. likely most/many users would not even notice it.
( * ) hmm, it be interesting to check the code of MIDI CC module, id not be surprised to see it have a slew?!