I am fairly certain that there's an option to cvs diff that allows you
   to exclude the ID line differences, so that patches that you submit
   can be applied to the master tree.

The only such option turns off *all* keyword interpretation.  This is
not useful for our purposes.

I've seen changes to RCS that allow selectively turning on and off
certain keywords.  I'd probably go a step further and make the keyword
processing fully generic, with a configuration file, so I can specify
a template for each keyword, or turn off keywords.