I have a Python script that will create a secure backup and put the files in the temporary folder on my Datapower using SOMA and the XML management interface.  

Now I want to retrieve those files using either the XM management interface or the REST interface and it seems like Datapower isn't allowing me to do that.  Is it possible?

You can't retrieve them from the box, or put them back into it for a restore?

You might want to check the default XML Manager.  It may not be allowing the XMI to export a document that large.