I have supported the GCC/GCJ and GNU-Classpath projects with a number of
patches which fix some problems of those free RMI-Libraries.
Particularly the interoperability of the free RMI-libraries with the
original RMI should be improved now. I don't know if you already run
JBOSS on "alternative" java implementations, but it would be helpful too
get some feedback from RMI-experts like you.