THANK YOU so much, i was even handling the camera in a specialist store where the owner could only say it was keeping the monitor on!
AF-S correctly enables the OFF mode both in pasm and the exr modes, only missing in SP
As the other poster noted, the screen will activate upon changing various settings ... besides the exposure compensation dial, how else would you know what shutter speed, aperture, etc. you had changed to? But as soon as you tap the shutter, the screen goes dark again.
The small wheel (which is the only one you touch by accident as the thumbgrip is too close) is only assigned a function in the asm modes and still turns the screen on in all other modes; the wheel should leave the monitor off then, or have a programmable function instead of being passive (also in playback mode where it would be perfect for shifting between photos)
Also using monitor off it would make sense to have the info screen showing when changing settings instead of the live view, since you just want to which number you are setting:)
Read through the manual again, these things are simply never mentioned, thanks for helping!
Useful tips and facts about Fujifilm X10: https://docs.google.com/document/d/1RYxbNsSGs2FtpkjpsLlA-yrkjXO_DKiBaVpMdLPA5P4/edit#
Collected user advice for all Sigma DP1 and DP2 models: