has already been very difficult to obtain a transient attack very similar to that of the magnetic pickups from the piezosimagine how much it would be difficult to get a convincing nylon string sound from the steelin the past I have studied the synthesis of sounds with various types of synthesizers working by: FM, subtractive, additive, sampling, and mixed techniques
one of the things I learned is that the transient attack is perhaps the most important and characteristic part of each sound, and it's that characteristic before all the others that makes us instantly distinguish one sound from another with eyes closed, if you took several one note recorded tracks each with a different instrument, and you cut out just the transient attack part of each one, it would be much harder to distinguish one sound from anotheryou can get an aproximate idea of what I said by using the HD looper and pressing the reverse switchby the way if you want to get very approximately a violin sound from the electric guitar (better if distorted) just cut the transient attack with the volume pot or pedal and use vibrato on your longer notes
The thing about the Variax is that it does use an ADSR system, at least on some models, though it might be more of just decay if anything. Like the Banjo, it uses a decay system to make the notes short like a Banjo.
I also believe they might be using an ADSR system to address the palm muting issue.
The problem is that when they do this, they need to do it without making the guitar glitch out.
Luckily they have a 6 pickup system so they can apply the effect to each string.
I think the piezos are alright, and it helps if you're using high quality piezos, which is what the JTV kind of does against the old Variaxes.
The whole point of using piezos though is because it's ideal for modeling.
I've seen a video about someone discussing how piezos have a flat and large frequency response compared to magnetics. It's almost like monitoring headphones but with guitar strings, if that makes any sense.
This is appropriate because that's exactly what you'll want when it come to processing something through pickup algorithms.convolutions, is that you'll want the rawest form of input from your strings you can get, else you'd lose character in the strings and not be able to model them correctly.
It does become a problem though when the behavior is a little off. Luckily Line 6 has helped it by combining the best piezo pickups they can get, with programming the sounds just right.