We've been talking about this on the RDM forums for awhile and I thought I should share. Would you cast magic more often if casting magic awarded you an additional attack that would TP while you are casting a spell? Think of it like Zanshin for spell casting, instead of for missed attacks. If you use a spell that also benefits from OA, then hopefully you will actually net gain TP, even if you don't necessarily net gain DPS.
We have a typical RDM quagmire going on where people are spouting their 'knowledge' of how the FFXI game engine works as a justification for why RDM should or should not melee, as opposed to actually talking about the idea. But for you guys, I doubt a debate on whether DRKs should melee will come up, so hopefully you can actually have a discussion.