I think that making it an 'other' chat will still be too general. Why not just have the general chat and nothing else then?
I actually think having an Animorphs Chat isn't a bad idea, for more Ani-centric conversations, and unless it's a huge amount of extra work on the mods parts I don't see why there can't be a chatroom for that and for RPG's.
I guess the way I see it, the major/most popular sections of the forum should have a chat to correlate with them. The General Chat kind of correlates to the General Board, the Media, the Bored Board, etc. Why not have a chat that correlates to all Ani-related convo, or to rp's? Both are huge parts of RAF with threads that are updated multiple times daily (whereas the projects may not need a chat because they usually do not involve a large number of people).
The problem with making it just an "Animorphs" chat is two-fold:
1) A person may enter and want to rp, but everyone is just talking about whether Marco and Cassie could ever pan out.
2) It would not be useful to any of the rp'ers in other non-Ani fandoms who would want to utilize it.
We already have one general chat, we don't need two. I think if you mods do decide to branch out and add any rooms, they should be more specific, not less.