No I confirm Thom that this command does not work on this Shuttle all-in-one computer.
The screen will turn off and on immediately (UI1) or goes into Flickr screen saver (UI2).
The only command that work is the "/usr/sbin/vbetool dmps off".
I have the crontab solution but I want a little more interactivity.
A key on the keyboard, screen or remote control would be more appropriate to turn off/on this screen.