I sometimes make hue a meaningful attribute in data visualizations, but try to keep chroma roughly consistent for various hues, so that varying chroma does not cause visual artifacts unrelated to the data. RGB gamuts are very limited in blue–green colors (when you additively mix purplish blue “B” and yellowish green “G”, it’s hard to make a bright blue–green), and as a result my whole data visualization ends up with relatively lower chroma than I would like. With an additional few primaries (say, adding a greenish blue primary and a bluish green primary), the chroma-width of the gamut would be much more consistent across various hues, which would let these visualizations be something like twice as intense. It would make a huge difference.

You probably haven’t seen any “wide gamut” demos with fundamentally different primaries involved; display manufacturers have been expanding their gamuts by making the three RGB primaries have narrower and narrower spectral power distributions, rather than by adding additional primaries.

For a while Sharp made a “4-primary” display, but the additional “yellow” primary was more or less created by an additive mixture of existing “R” and “G” spectra, so didn’t really make as much practical difference as one would hope. https://en.wikipedia.org/wiki/Quattron

You can get a display with like 8 or 10 primaries if you run a color science research lab and can spend tens of thousands of dollars on it (or maybe more? dunno).

I'm sure if I saw a 10 primary display sitting next to an RGB one for reference, I could tell a difference. But if it was just sitting there by itself, in regular non-ideal viewing conditions, I doubt I would think that it is significantly better than normal displays. Whereas for high frame rate and high brightness/contrast displays I can easily see a big improvement under normal non-ideal viewing conditions without needing a reference.

Again, it would depend on the content shown. If you watch a 24 frame/second video on a 120 Hz computer display, I’m not sure you’ll notice much difference. If you use an extremely high contrast display to show a low-contrast image, you won’t see any obvious difference. If you use a 4K display to show a 240p video, you won’t see any obvious difference. If you watch a video with monophonic sound on a 7.1 sound system, you won’t hear any obvious difference. Etc.

If you look at a photo produced by an RGB digital camera, color graded in some standard RGB space, and then presented on an RGB display vs. a 10-primary display, you aren’t going to see any obvious difference, because the content does not take any special advantage of the medium.

In comparison, if you look at a bunch of synthetic images created to highlight the differences / stretch the capabilities of the displays, or e.g. a video produced by a whole hardware–software–author pipeline expecting the more capable display, the differences will be pretty obvious.

High frame rate benefits all interactive content, and touchscreen interaction especially. High brightness and contrast benefits most content generally and practically all content under bright viewing conditions. But even if you upgraded all of your content to high gamut, I think only a small fraction of it would benefit in any noticeable way.

It would be noticeable if all content authors were experienced in the medium, but in the transitional period there would be little obvious difference, because the entire culture of digital imaging, including almost all existing content, is based around the limitations of RGB displays and images.

If you want a somewhat relevant test, you can try comparing images produced by a photo printer with images printed in old newspapers. Having a larger gamut makes the former much more vibrant.

Current displays produce very intense orangish-red, purplish-blue, yellowish-green, and reddish-purple colors. So the differences with a hypothetical >5-primary display are going to be most noticeable in the blue-green range, and oranges and yellows.

I think it would only be useful if the colours on the screen have to match colours off the screen.

If all you're paying attention to is what's on the screen then it probably doesn't matter much exactly what those colours are because it's all relative, your brain compensates for it, and it's not as if the cells in your eye have a consistent response to colour in any case: it all depends on what you've been looking at recently.

If you've ever been in a television shop, back when they still had shops, you could find two screens next to each other showing the same television channel but with radically different colours, when you compare them side-by-side, but if you watch just one of the screens - it doesn't matter which - you get used to the colours of that screen and everything looks fine.