I found a 42.0MB update with version number 6.16.215 for the Droid Razr/Razr Maxx.
THIS WILL ONLY INSTALL OVER STOCK 211, IT WILL NOT INSTALL OVER ANY ROM.
Instructions:
Fastboot or RSD back to stock .211
Root .211 with whatever method you choose
Download and Install Voodoo OTA Root Keeper
Backup Root
Temp unroot
Flash Update in stock Moto Recovery (Not bootstrap or safestrap)
Restore root with Voodoo OTA Root Keeper
PROFIT
FXZ IS POSSIBLE!!!! You can flash back to 6.16.211. Credit to iDroidGuy for testing it and for the screenshot below.
Rooting can be possible using the method included in the Droid Razr Utility version 1.8.

--Sam