I can downgrade to CAT 2 if something screws up.
in the computer game without a doubt. in real life CATIII requires autoland and CATII not.
so when something "screws up" with the CATIII app its a far better idea to go around than take it manual and "downgrade"on "borderline CATII" like you wrote.
of course the whole discussion is only valid if the AC has an autoland capability.
cheers