I was able to use this tool to downgrade to the original 4.1.2, root, protect root and update. I was not on 9.20.1 though. I was on 9.18.79. That should not really matter, but I am not sure.
Sent from my DROID RAZR HD using Tapatalk 4 Beta
Yes, that is the big question. I haven't received a definite answer, however it's looking like if the stock phone has 9.20.1 it cannot be SBF and start from scratch like I used to do with the Dx.
Maybe someone is working on a new root exploit, who knows. In my experience though, as interest wanes in a certain model phone, developers tend to follow the flow.