I understand completely that conversion to Pure ODD is a big deal, but is converting <datatype> to <dataSpec> going to have a much larger impact than using <elementRef> instead of rng:ref, etc.? My point is that conversion to Pure ODD is a big deal either way, no? I think you're right, project management, and maybe even some money, is in our future. (And I can already hear Hugh muttering "git-fork" under his breath. :-)
my heart slightly fails me when I start thinking about the side effects of dropping <datatype> and converting all the Guidelines to <dataSpec>. The existing .odd files out there stop working (potentially), Roma stops working, as does its little cousin Byzantium, the documentation of the Guidelines probably gets hosed, a small myriad of utilities fall over.
I hate to say it, but changes of this scale need a bit of project management.
else you need a team of dedicated people fixing things on the fly.