Probably worth noting that in clojure you can have actors if you like (either in clojure, or using some library - even akkasource.org) - likewise, there is STM in scala (see same link) as a library. It isn't one or the other.

I really love clojure, but as I have said to others, have given up hope that a new type of lisp will catch on for more than a very small group. I would LOVE to be wrong about that.