Doggiehowser:
I'm confused by your statement that "it" (presumably the latest update) over-writes the entire firmware and is therefore not cumulative. To me, "over-write" means the new firmware replaces the firmware or data previously located in a given space on the drive. "Cumulative" means that the latest update includes all prior firmware as well as the most recent changes. If the latest update is not cumulative, then it has only the latest changes and, if it over-writes all existing firmware, then only the latest changes will remain. I think that either (a) you meant to say that the latest update is not "additive" or (b) your meaning of "over-write" is that the newly installed firmware merely adds to firmware that is already present. Is that correct?