I wonder how those poor women deal with RGB displays. It must feel weird to see a difference between red+green and actual yellow.
Although, on second thought, color vision doesn't seem to work perfectly anyway. I never understood how red+blue can be perceived the same as far violet, it just doesn't make sense if you look at those frequency response curves.
I doubt it will be that bad. It will probably seem a little more dull, like some of the colorblind simulators you can find around the net. It's probably not just screens; pigments have the color they have because they reflect certain wavelengths, tuned to the proportion that a trichromat would consider identical. A tetrachromat is almost certain to notice that pigments of pictures on paper might be drastically different in color to the color of the objects the pictures are supposed to represent.
The brain doesn't perceive color just by addition of the stimulation of the cones. Your red and green cones are still (slightly) stimulated when you see blue, and your brain tells you that blue is the color; with violet, the stimulation among the cones have a different proportion, hence violet. Incidentally, this is also why the sky appears blue; the sky is too polluted by other wavelengths to appear violet.
Actual violet (like UV LED or mercury lamp) should stimulate almost exclusively S cones. But it turns out that if you take blue, which stimulates M and L more than violet, and then add even more L stimulation, you end up with something that "feels" more violet than blue (at least to me). This is what bothers me. It looks like two distinct inputs producing the same output, even though there exists an intermediate input which produces different output.
You aren't paying attention, by "inputs" I meant "inputs from retina to the nervous system", not "inputs to the eye".
Most metamerism can be trivially explained by different combinations of light stimulating cones in the same way. But it looks like red+blue and violet are different and there is just no reason for them to be perceived the same, except that apparently there is also no reason to distinguish between them.
None of the red cone sensitivity plots I've seen previously showed secondary peak, but that's because they were always cut somewhere in the blue region.
Although, on second thought, color vision doesn't seem to work perfectly anyway. I never understood how red+blue can be perceived the same as far violet, it just doesn't make sense if you look at those frequency response curves.