You know that most of the 'robes' in Naxx are exactly the same as your current dre- I mean um... Ballgown? Anyway, there can be greoups set up for 10-man, but as is the way, I guess there needs to be a consistent leader/one who can raise spirits enough to get people going. The thing we tend to struggle with are the tanks and healers, though, which even with regular promotion leaves raids a little thin (most healers will try and save that character for their guild run, or else try and go to Naxx 25-man). My two characters capable of healing aren't dedicated to it, and so I can never promise that they'll be able to do so (though I'm willing to respec if the raid looks as though it'll go ahead).
Meh, I think I'm rambling.