I liked your explanation of SQUICK. However it illustrates a problem. Material that sets off a SQUICK alarm does not always actually contain the elements concerned.
I can illustrate this by reference to my recently posted story: 'Checkout'. Checkout is coded as nc (non-consensual), but there is actually nothing nc in it. Checkout is about the limits of consensuality, volition, persuasion and all those related things. It is coded as nc because it involves physical violation that results in death, but that is not the same thing at all.
Checkout is also coded as 'snuff', but according to your definition, it doesn't contain snuff either, as there is no kind of murder or violent execution. People who enjoy violent nc would not like it at all. It portrays how excitement, and particularly sexual excitement impel us to do certain things in spite of having a certain knowledge of the consequences.
I have also read Sade and Masoch, but in French one of my favourites was Cecile Saint Laurent, whose Encore Clotilde was one of the most erotic works involving bdsm I have ever read. If you can tell me what kind of knot he called a 'double clef' you will be my friend for life. I translated it as a clove hitch, in my simple way, after failing to find a better translation.
If that was your first post, I was seriously impressed, and I hope we will have a lot more to talk about!