@Robert. Some of your ideas seem to be leaning toward a much more powerful / versatile effect than the version that is currently proposed. I’m not opposed to a more powerful effect, in fact I would favour such as an optional (download from the wiki) effect. You may be interested in having a look at the code in this much earlier version: More versatile Nyquist fade/amplify effect
The currently proposed version is the result of very long discussions about how to simplify the effect so at this stage I’m not keen to add more features. Gale has tended to push toward greater simplicity, yulac toward more sliders and presets and myself toward flexibility/functionality. I think that the current version is very close to a balanced compromise in that it offers a good amount of flexibility/functionality, has some sliders and presets and is about as simple as we can get it without unduly compromising the other two forces.
In a strict mathematical sense it is neither.
The curve is mathematically something like: y=(cos x)^(1 / (1 + c))
where “c” is the displacement above 50% Mid Fade Cut/Boost.
In practice, it is a “little more curved” than a cosine curve (like a cosine curve with the middle “pushed up a bit”).
The practical case is that if you want a “medium” amount of “upward” curve (like a bullet rather than like a trumpet bell) then set Mid Fade to 50% boost.
If you want a fade out to stay louder for a bit longer and then curve down a bit more steeply, increase the Mid Fade a bit higher.
If you want it less curved (more linear) then reduce the mid fade boost.