What insights do you gain by experimenting with different implementations of Common Lisp? Can you share some of those insights or things you learnt by experimenting with different implementations of Common Lisp?
I experiment more with different versions of Scheme: Gambit, Chez, and Guile. I really like the Racket ecosystem - a lot of good work is done around Racket. I don;t much use Clozure (except for my hobby site cookingspace.com) unless I am using it because that is what a customer uses.
Church, for Probabilistic programming is interesting but it was apparently been supplanted by WebPPL(which is not a Lisp).