Well, hopefully there will be fic in both - and it's only two... I thought it better to make one smut and one not because I know there are a lot of people in this fandom who are all ewwsmut and another lot of people who don't like fic at all. General fanfiction communities - multi-fandom, I mean - often also prove impractical because your flist will be spammed by a lot of fandoms you never heard of or don't care about.
What's a C&D?
The MPAA ratings are widely used by fans to rate fic and art, and are much better known than the FF.net K, K+ and so on ratings. Furthermore, the latter is used for fic, whereas the former is often (mis)applied to all sorts of creations. I really don't think there should be a problem with non-Americans not recognising them. I can't think of any more recognisable system, for one. What would you suggest?
Thanks for the input, btw, I really appreciate it!