Feel free to correct me if I'm wrong, but what would be the harm in trying to flash the
MF1 pre-release? From everything I read if it's not going to work then the installer will just fail to install anything and shouldn't brick your device. If something does go wrong and it messes up your device, we now have the
Odin package to get back to ML2. As a last resort you could always
go to Best Buy and try to get them to reflash the device to MF3.
I know that people were able to flash between
MI2 (4.3) and MF1 (4.2.2) no problem, they were even able to obtain root on MI2 so maybe there's a way to downgrade from ML2 to MI2 to MF1. I have no idea if it would work, and odds are it won't but it seems like it's worth a try.