The Fez team are working closely with APSR partners in establishing guidelines for the import and export of objects between Fedora and Dspace. Scott Yeadon (a DSpace core developer at Australian National University and APSR Partner) has created a METS to Fedora METS parser which works with the soon to be released DSpace 1.4.
Working with Scott we are now at a stage where Fez/Fedora can export a METS object that DSpace can successfully ingest, and Dspace can export a METS object that Fedora can ingest.
The problem now is that DSpace uses a different content model to Fez. The Fez team is investigating where we can bring the best practice of Fez/Fedora and DSpace together to have a united content model. This will probably use the APSR National Library of Australia METS model for MODS and PREMIS support using the PRESTA guidelines.