To add to what my companion said, if you look at what and how we link you'll find that there's probably only a small percentage of overlap. I understand concern about the possibility of competing communities but metafandom and meta_roundup do have very different criteria for linking and very different ways of presenting such links.
I'm about to go over and friend meta_roundup because it DOES have plenty to offer me that I would not get simply by participating in metafandom.