Yup. They've updated the article. Quite a bit, actually.
I did find one interesting tidbit:
"Please note that Recovery HD must be present on your computer's startup volume to use FileVault 2"
This tells me that when FileVault is active, you boot off the recovery partition, unlock the encrypted partition, then login is passed along to the booting of the encrypted partition.
So...if we could figure out how to boot to the recovery partition *and* bring up System Preferences then we could possibly change the login window to userid & password.
Failing that, I think you can open the Terminal in the recovery partition, so if we could find the command to change the login window we should be able to do it command-line.
I don't have time to mess with this today, but perhaps someone else could and report findings back here.