Mind that CRTs had a viewing distance, much like the subject point in classic painting. E.g., at this distance, dithering tended to blend into a solid tint on common consumer CRTs. (The granularity of a shadow mask is generally smaller than that of a pixel/PEL, so there are actually two kinds of rasterization involved, which helps blending. The effect also depends on the shape of the mask, as in round, oval, square holes, or even a Trinitron-style wire mesh.) Also, the expectation to actually perceive CRT colors when reproduced on a modern panel may be overly optimistic.

I'm generally impressed by these shaders (they are about the best, I've seen), but I also think that colors are too muted and that the mask is overrepresented.

Edit: Regarding CRT intensities, mind that a CRT set up for daylight viewing would give you headaches when viewed in the dark, which is hard to achieve with a modern display panel.