First, some useful additions, e.g. the channel swapping. We could see color overlay as the every-day-use effect (the idea was to keep it simple), whereas color overlay 2 serves as tool for pros, for the ones who need more control to tweak their colors. Really nice.
An additional fun thing thing about the effect (also with tulamide's Color Overlay) is that the values don't have to be between 0-100% . This might not be intended, but it's again quite useful in achieving nice color effects. This is as close as I'll get to color swapping, and it requires quite a bit of probing, but the recoloring possibilities are impressive.
It was connived, but the results outside 0-100% may differ unexpectedly from what one has in mind, so it is a "handle with care"
I'm currently (and because of design issues probably a little longer) working on an effect, that does color indexing, meaning swapping whole palettes of colors. It works fine but is limited in the way of initial coloring, so it will take a while to figure out a good and convenient way. Maybe I'm posting a test version to see what input comes from the community. I'm not sure.