(Yes, this is an addendum to the original question (which I did not pose).)
As you have used both extensivly, could you come up with some simple speed benchmarks? Also, which one scales better under load (think very large number of hits)? And which one has a smaller memory footprint? Yes, I agree power and expressivness are important... but they are not the whole picture (<jest>if they were, everyone would be using Lisp *ducks* :-D </jest>).
Update: Added <jest> tags (because I realized what I wrote could possibly be taken seriously (which I did not intend)).