I've since discovered that docbook-utils supplies a better maintained DocBook-to-man converter, in the form of docbook2man.
Interestingly, docbook2man is in fact based on docbook2X. I'll leave this bug report open until one further issue gets resolved: docbook-utils (docbook2man) uses docbook2man-spec.pl rather than docbook2X's newer conversion tools. docbook2man-spec.pl is SGML only, while the newer ones support DocBook/XML as well. I've raised this question at http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=189951 When it's resolved I'll be happy to close this RFP. Drew