I'm concerned: we are already working with two libraries (the one we inherited from LJ, and the more recent jQuery). If we add dojo, that's yet another series of behavior/syntax/rules that devs will need to know, depending on which page they're working on.

I don't think they they'll conflict as code (well... the current/old JS library might :-) it messes up jQuery something fierce, unless you load jQuery first, haven't tried dojo), but I'm worrying over fragmenting the dev efforts this way.