AFIAK this should only be an issue if "Softproof" is used with a monitor profile.
I think you are right, it must come from the monitor.
So, I need to use Rawnalyse or Rawdigger, because I've taken some shots with my RX100 which are clipped according to the camera (RGB histogram and white blinking).
After loading them in LR4, I see a headroom of one full stop !!!
Strange because the contrast and saturation of the jpg is set to low.
And today it's a Scottish weather with low contrast and dull colors.
Will compare with my G15.