[INFO] DeRing vs DeHalo?

[shijan]

I usually prefer do not use DeHalo filters because they are known for additional artifacts, especially if there are huge solid black areas or black frames. But same time i really hate those oversharpened edges on DVDs and DVs. So i experiment with DeRing filters and seems they clean up things way better.
Just curios what is the fundamental difference between DeRing vs DeHalo? They seems do the same - detect edges and filter things around them somehow.
So what are "correct" situations to using each of those filters?
Any risks if use DeRing as essential filter for DVDs (in similar way as Deblocker)?

Here are some examples (SD upscaled to 1080p with NNEDI3):