I bit the bullet and unfroze everything. Took the update without issues and lost root.
I can't try to re-root until I get home tonight, but I have heard we did NOT lose the ability to root with this update. I doubted that anyway, since the more current Moto phones are still rootable.
EDIT/UPDATE: Someone turned me on to a market app called Voodoo RootKeeper
that will allow you to back up your root files, unroot (or hide the fact that you are rooted), take the OTA and then reroot without all the fuss. Too late for me, but a heads-up for the rest of you