Seeking consensus on dh

Sure you could, but given the impedance mismatch (RPM specs include some things Debian's don't, and vice versa; embedded scripts contain Redhat/RPM-isms, etc.) it'd make more sense to build a debian/ subdirectory from it.

The other way would be to process the RPM spec with, well, RPM, and the re-package the resulting RPM binary package to a .deb archive. This is reasonably simple to do, and flexible enough when you allow the user to edit the intermediate result.

I leave the question of whether getting RPM to run on Debian systems would be easier than writing a spec converter to whoever tries both and compares the effort involved. ;-)