Remember that SODA is not a separate repository to NAA. All the images you see on SODA are being prepared for inclusion in the full NAA collection and will be searchable through RecordSearch. Its purpose is mainly to highlight what is new because many users will not know to search for something that they are not aware has been scanned.
SODA can also be useful as a digital image viewer for any NAA record (even ones digitised many years ago) if you know the barcode. (Caution: The barcode is not the same as the control code.)