Thanks for your comments, guys.  I was beginning to think the lack of response indicated that I'd asked something either heretical or painfully obvious.  :-)

> That's my understanding as well. oai_dc predates the defining of the 15 legacy DC properties in the dcterms namespace, and it's my guess nobody saw a reason to update the oai_dc definition after this happened.

This is at least part of my use case — we do a lot of work with OAI on both ends, and oai_dc is pretty limited due to the original 15 elements.  My thinking at this point is that there's no reason we couldn't define something like "oai_dcterms" and use the full QDC set based on the updated profile.  Right?

FWIW, I'm not limited to any legacy ties; in fact, my project is aimed at pushing the newer, "DC-sanctioned" ideas forward, so I suspect in my case using an XML serialization that validates against http://purl.org/dc/terms/ is probably sufficient (whether that's RDF or not doesn't matter at this point).

So, back to the other part of the question:  has anybody seen a MODS <—> DCTERMS crosswalk in the wild?  It looks like there's a lot of similarity between the two, but before I go too deep down that rabbit hole, I'd like to make sure someone else hasn't already experienced that, erm, joy.

MJ