Oh, I just meant as a unit to be displayed to pilots/astronauts. That would have been the only difference noticable to a AGC++ user anyway. As an engineer I am well aware that most things are calculated in metric nowadays, here in Germany anyway. Documents about mass properties of the CSM still used scary units like "slug" or "stone".

Nowadays even most US companies work with SI units.
Aircraft that fly into Chinese airspace have to change their displayed altitude unit from feet to meters. And they have to slightly adjust the flight level, too, FL300 is not exactly a flight level in thousand meters. But in most other countries ft, ft/s and NM are the standard for these things. Russia is even transitioning to feet based flight levels.