I just wrote an email to a friend that started out as a note and turned into a speech.
I spent some time on both. There is nothing unusual about either of them. (a) they still depend on the JVM (b) for whatever functional goodness they profess to have they depend on the JVM and more importantly they are still inheriting from libraries that use the standard JDK. So unless they and your app use PURE scala or clojure libraries (see that Lift uses Jetty) it's just a non-event for now.PS: for all the benefits of "private" and "protected" was once thought... it's a waste of time. (a) people have access tot he source. (b) people want to see the implementation details as part of "full stack awareness" (c) people need to profile and build everything from scratch (re PCI).
JITs are making their way into most languages and they are really fast. I like the performance of tcl, Lua, Python, perl and Ruby... (I think I've decided that I like Rails but I do not like the Rails movement; different things). The fact of the matter is that everything scales in all directions. Just make it easy on yourself and reduce the amount of code.