[TextMate] Updating TextMate?

As I slowly customise TextMate by altering the bundles in ~/Library/Application Support/TextMate, I'm wondering what happens when TextMate is updated with alterations to the default snippets, macros & commands?

To get the benefit of such bundle updates am I going to have to manually edit my bundles in the above location to include the extras in the new bundles? Or do the bundles in the actual application package have effect to the extent that individual elements therein have not been overriden by anything in the user's Library/Application Support directory?

I hope this question is clear...

bongoman