Assuming you get the crypto right, and though it is quite doable it is not a certainty, the usual one would be people adding things that are impossible or highly improbable. This can be in general or at that stage of the game. If I was tasked with securing such things I would probably also run a compare for any online save backups as well (zero play time advancement and suddenly you are bedecked in the best available too you....), though there is no evidence MS does this for saves, profiles may well be a different story.