[Soli]

Meetoch. Stop trying to reinvent the wheel.
If your display supports rgb full then you set xrandr to full, and XBMC to full. That is the best way and the only way. Then you adjust your display to get it right. This gives the best quality in XBMC, and it looks right when you are logged on to a normal desktop environment. The xrandr command can be set as a global init.

If your display does not support rgb full, then you'd still have to sett xrandr to full and set XBMC to limited. That is if you want the best image quality in Kodi. (Unless Kodi use a 2-pass rgb to rgb conversion, which would be a strange thing to do) But the desktop environment would look wrong with xrandr set to full. If you're using kodi-standalone then I would suggest having a xrandr set rgb to full when starting kodi-standalone, and rgb to limited when starting the desktop environment. ( If you're using chrome launcher, then you'd need to use a custom script to set the correct level when starting/stopping Google Chrome from within xbmc)

And Stereodude is right, and the post that you are referring to is wrong. (and the rest of that post is not entirely correct either)