Yes, the link above was in response to your statement about storing test data.
DevForce works the best when the primary datastore is a relational database. We provide POCO integration to allow people to bring in other adjunct data and have it managed in the same way as a DevForce Entity, but if that is your primary use case, quite a bit of the DevForce value is lost. Do I understand correctly that you want to have the same "schema" hosted by a database sometimes, and by an XML file other times, and you want to be able to toggle between the two?