Hi,
If you want to know more about the design choice of SAP re. the Export DataSource, I suggest to ask SAP by creating an SAP Support Message. In my opinion it contradicts with the purpose of a Virtual Cube.
If your purpose is data staging, then I really advice you to go the standard way.
As I already mentioned in my previous reply: Function Module RSDRI_INFOPROV_READ does not work for a Virtual Cube. Please refer to the on-line documentation of the Function Module.
Best regards,
Sander