It would seem appropriate to allow for field mapping from Source Data to destination node on import.
My example: I have to import a large user base from CSV, user import works great but I have related data unique to each user: Address, City, State, Zip, Phone, Etc... It would be useful to be able to map additional data to fields when importing.
Ideally it would work as importing users from CSV followed by adding additional import functions and choosing where the function will dump its data from a select list of fields.
Ex: Mapping Source Label: Zip | Target: field_zip(Profile)/field_zip(Location)
and I would be able select field_zip(Profile) as its the appropriate field even though I use a duplicate field in the Location Content Type.