I wrote a medium sized project in clojure at my last job and it was a good experience. The team was small (under 5) so the hiring and training wasn't an issue for us. I never had a problem reading clojure code, and the only major headache I can remember, which was our fault, was that clojure keywords (think ruby symbols) used to be turned into interned strings which are stored in permgen and we were running out of permgen space. I believe this has been fixed in recent versions of clojure, but I'm not 100% sure about that.
So does Erlang, but it's not really a bug. Symbols (atoms, whatever) are guaranteed to be a unique identifier, so the fact that they're allocated and exist for the duration of execution isn't really surprising.
http://eigenjoy.com/2011/03/02/clojures-keyword-can-fill-up-...