This is something people have been asking for on Voat, and probably Reddit, for a while. Especially now with people on Voat figuring out how to brigade themselves, it's desperately needed over there.
Having it here would not only be useful for the same reasons, but also give us an edge in bringing Voaters here.
We actually have an open task in our tracker to add custom sorting options to comments like we do with posts. Another thing we have pending is 'burying' comments...