If you use the Leitax adapter, can you seamlessly go from the Nikon to an OM body? Or do you have to reconfigure the lens mount?
I keep the OM to EOS adapter on the 5D2 and just switch lenses between it and my OM bodies.
With respect to "another DSLR body...", to quote Bill Clinton, "I feel your pain." I got a 5D2 on a lark in the week following Christmas, I got what I thought was a deal. That purchase was funded by the sale of a D3 I just wasn't using.
Fast forward 5 months and now I'm struggling with the functional issue that I LOVE using the OM bodies and the 5D2, all and only with my OM Zuikos, and an emotional connection I still have with many old manual focus Nikkors I've had for a long while and the D700 for them. For the first couple months this year I regularly went back and forth between the digital bodies. Of late I have used only the 5D2, often forgoing my pair of M8.2's, too.
With respect to low light IQ, I feel the D700 & 5D2 are about equal up to ISO 4000, by ISO 6400 the Nikon is better. The Canon doesn't fall apart @ 6400, it just isn't quite as good.
Film is a much easier issue (for me), it is either an OM or a M, period, end of discussion.