I wonder if you known IEEE Learning Obejct Metadata.
Is a specification of metadata for Learning Objects. As you known we are developing a LO Repository based on Alfresco.
The LOM XML schema is quite complicated.
At this time I use JAXB 2.0 to bind Xml Schema with Java classes.
I think at the moment is the right solution to manage thi kind of content. Maybe in the future release of Alfresco will be simplier to manage structured content.
What do you think about it?
P.S. : About that there is a Alfresco Forge Project called FreeLOms!