[A complimentary Cc of this posting was sent to

], who wrote in article :
My guess is that to do otherwise would increase the chroma noise too
much. Chroma noise in digital cameras at high ISO is already
intrusive, and anything that increases it may be unwelcome, even if
sensitivity improved. Without direct experimental data it's hard to
say.

When I look on the digital images of a gray surface (those of "compare
two cameras" kind), it looks like my perception of noise is not
related to chrominance noise at all. At least a camera with higher
measured individual-channel R/G/B noise can produce much lower visible
noise if its noise reduction algorithm favors luminance noise (as
confirmed by luminance noise graph). Of course, it is in no way
scientific conclusion, but I may have seen about ten such
comparisons...

The other issue is how well non-RGB filters could be made to
approximate the colour matching functions of typical display
systems.

AFAIU, this has nothing to do with display (output) system, but only
with input system (cones). As far as the filters match cones, you can
postprocess colors into *any* display system (if the initial color is
in the gamut of the display system).

And if you do not match the cone sensitivity, colors which look the
same will get different when stored. After this no amount of
post-processing will be able to fix this.

Hope this helps,
Ilya