I'd never heard of AO3 until Yuletide (and accompanying wank), so Xposting means more readers, which can't possibly be bad, amirite? :D

In this case, I'd say you're probably gonna have to write it yourself :( (I went looking for Avatar pronz, and of the 8 or 9 fics, only two were relevant to my interests. Sad. I'm in for porn battling now.)