I like the idea of composing subclasses of C::A into the larger application, but I didn't see how you implemented this bit of the 'technical specification':

"...so it's easier to just disallow the whole C::A than it is to disallow certain run-modes."

If REPORTS => reports.cgi is in the navigation template on every page, then how do you prevent the user from executing that particular C::A? And I don't think that

  # Display some method of choosing reports, probably with some author
+ization
  # checks in there
[download]

inside sub choose counts; it's still disallowing a certain run-mode named "choose". :-)

p.s. I enjoyed and learned something from being sidetracked by http://www.mail-archive.com/cgiapp@lists.erlbaum.net/msg00849.html.