Lock shared project objects at the "record" level

I know the product stores objects as XML and you handle "locking" by checking out entire packages. To make a shared project workable, this forces users to create many packages that make little sense to have separate. It would be a better user experience to lock at the "record" level (the particular Use Case, Requirement, Diagram, Definition,etc) on which a user is working. I realize that this may involve using an actual database rather than separate XML files, but this may be a more robust approach over all for the software.  MySql might be a good candidate.