I follow you completely!
What is the sence of tweaking the gamma to the perfect 2.2 if this introduces jumps in the grayscale, you may not forget that the gamma of the LCOS is around 2.1 and every kind of tweaking through the user menus is done through look up tables in the Silicon Optix processor only operating in 10-bit, while the LCOS itself is doing its gamma in 12-bit. So all kind of little tweaks could result in contouring artifacts. So I prefer a little off gamma, but smooth colors/gray rendering without any jumps!
The same is through for the CMS, this CMS is doing so much calculations in a questionable color space (HSL), what are the errors introduced due to rounding? Like I mentioned before on this forum I've seen allready 2 scenes in the movie "Hard Candy" showing severe color contouring artifact I don't see at all in THX mode. Maybe THX is doing their CMS in the RGB space? Maybe that is the reason for the short black screen when switching to THX? So I prefer a little less accurate THX mode next to a perfect CMS calibrated mode having color contouring artifact on some smooth color transitions! And by the way, I measured the THX mode to be very close to Rec.709, even a little oversaturated.
What my point is, getting a "film-like" experience is only possible by avoiding all kinds of digital rounding errors generated by all kinds of tweaks just to get a perfect measurement. You may not forget that our eyes/brain are "specialized" in adaptation, for example if the x,y coordinates are a little off of white, our brains will eliminate this. By the way, how many movies have natural colors these days? So if there is a little error, who will ever know. While on the other hand if there is a contouring artifact, everybody looking for quality will notice it.
Just my opinion...