What advantage do you perceive there is in reverting your DVR-216L back to a DVR-216D?
None whatsoever. My drive just gave up the ghost after only 3 months of use. I contacted the seller about it and they are willing to take it back under warranty. I told them I had flashed the drive, they said set it back to default if at all possible. Since they are aware of the firmware flash and are not bent out of shape about it, I would like to set it back if at all possible as per their request.
I do not think the flashed firmware is what caused the drives death anyways, just random bad luck on my part.