In case it isn't obvious, this is mostly about my site. I implemented it in Kawa Scheme.
That's pretty impressive... How did Kawa Scheme treat you, if I may ask? I have always been a little curious about Lisp (or Scheme) implementations on the JVM (clojure included) and figured you might be a good person to ask...
I'm very happy with Kawa Scheme. It's very fast. It's stable, and has everything from R5RS that I care about. The only drawback is it's so good that I don't experience enough pain to push me to update to new versions. I see on the mailing list all the good improvements, but I'm still stuck at Kawa 1.7.