Creating this feature request on behalf of our customer:

We have quite a lot of article security settings tied to reader groups that make it time consuming when we need to create a new one. It would be great to be able to copy an existing one as a starting point so I wouldn’t need to go back into all the articles and set things up for the new reader group.

Either that, or it would be nice if I could assign multiple reader groups to a reader and have their security settings combine. That way I could mix and match.