There is probably good beer *somewhere* in Orlando ...
Consulting in Model-Based Development, Transformation, and Object-Oriented Best Practice http://www.cintegrity.com
Meaning you would vote for the XMI? I had planned on tackling that in my current work ... I just didn't want to do it first.
My impression is that every tool has its own little quirks about XMI so that I am going to have to specifically support a given software, except by chance. I know that I have had non-trivial difficulty moving models to and from RSA and EA, despite EA having some RSA specific import options.
And, yes, while the initial desire is only a component model, there is interest in some automated diagram generation. Nomadesoft does this in their branch interpretation.
The XSD is at OMG, I presume?