Not convinced that we can get all your HP TRIM content out and move it to a new enterprise content system, like SharePoint?
The solution to your question is to make use of the integration API between HP TRIM and the other business application. This integration approach seems to be the new core business of ECM vendors anyway.
With Xillio's developer API, your organization will end up with a solution that brings you the best of both worlds. In case of HP TRIM - Sharepoint integration: Document Management in SharePoint and HP TRIM for your Records Management.