Re: Compile flag. Don't hold off on implementing a flag if you want to, but it might be worth hearing from others whether such a command line option is even desired. I was asking in hopes of eliciting such a response.
For the way that it is handled in the Clojure compiler, search for REFLECTION_WARNING_PROP and related code in Compile.java. If you invoke the Clojure compiler directly via a Java command line, use -Dclojure.compile.warn-on-reflection=true (default is false). See the recent email thread sent to Clojure Dev Google group if you want to know how to do it via ant or Maven. Link: https://mail.google.com/mail/?shva=1#label/clojure-dev/13aa0e34530196c3
There is also a separate command-line flag called compiler-options (see Compile.java) that is implemented as a map inside the compiler. It was added more recently than warn-on-reflection, and might be the preferred method to add more such options, to avoid having to continue to add more arguments to the pushThreadBindings calls done in several places.