The great thing about OBD for older cars is the other things you can do with it. There's lots of applications (not just in the ecomodding world) that would find OBD useful. For example, I may be ecomodding my Smart Roadster but I have a track car that doesn't have OBD and would benefit greatly from being able to interface with
RaceChrono, which supports logging RPM and otehr parameters via OBD. I'm sure there's many more potential areas of use, too.