It’s fairly simple (just tedious) to cordon off my changes in the usf/ush files and put them behind a bunch of if shading model = x then statements and restore the normal default lit behavior.
I don’t do that because there’s no situation where I’d want that, and it’s a big timesink to write the extra code to define a new shading model for certain behaviors, and then change the shading model dropdown in every single material to the one I want, but it’s not difficult to add if you wanted to.
You could use customdata1 to do the same thing but there’s not really a point because you’d still be going through my changes and placing a bunch of if thens, and just using that value instead of the shading model enum, so there’s not really a good reason to do it that way unless you wanted to lerp between the two shadings.