Aha, this could be the key as MPPS wont calculate the checksum for the rs6 ecu. Maybe this is why it has to write the whole file.... I'll fire up the v13 software to check too, but i think v13 is really just rebadged v12. of course my v12 could just be rebadged v5 though
1. It will calculate the checksum fine.
2. Write the RS6 ECU as a RS4 with ME7.1 protocol and it will only write the changed blocks.
HTH.