I'm looking at how we develop DITA to handle the content of our research reports, which will need some topic specializations, so it's not a rush job.  In the meantime my colleague, our knowledge manager, is developing a document metadata architecture that will make our legacy documents searchable.

Have you introduced DITA into an environment that already had a document metataging system in place?  If so, what precautions did you have to take, or changes did you have to make, to ensure that the two worked concurrently without clashing?