How can you export/import a content store excluding the Cognos namespace

[mh120]

We are upgrading from Cognos BI 10.1 to 10.2 and need to change how we implement our security.  If we import the existing 10.1 content store (full export/import) into our clean 10.2 install, the out-of-box delivered 10.2 Cognos namespace is overwritten by our existing non-standard (badly customized over the years) 10.1 Cognos namespace.  Is there a way to import everything except the Cognos namespace?  What are the dangers/risk of breaking existing user content (and any recommended fixes for this)?