If you're going to make scientific observations, you probably want to differentiate individual wavelengths via spectroscopy. Lumping bands together doesn't allow you to differentiate emission lines that would help you determine proportions of constituents. If you're going to go with spectrographs, in selecting your bands I think you need to consider what it is they're including and excluding. Filters that overlap will indeed have cross-contamination from other emissions, which illuminates the value of square filters. They have no bleedover, so you know the level you measure is only the intended bands, and the grayscale spectrograph you create is only the intended science.
Esthetics is an entirely different matter--and indeed, color vectors captured in a dense color space (with overlap for every wavelength) will better fill the sRGB display space. The only problem is determining how to go from a 5-dimensional space to a 3-dimensional space...
BQ
Although one of my goals is actually to dabble in some citizen science, my primary goal would still be imaging. I know this is cringe, but I like the idea of optimizing for "meaning" and "interpretability" in an image, as Frank says, rather than for clicks on Social media. I want to image to quench my curiosity (which does lie in NUV & NIR as well) in how I could do my part in capturing the universe in as faithful and meaningful way as I can.
So getting back to filters and color diversity. Earlier I was thinking of going with the square cutoff UBVRI filters and mapping U+B, V, R+I to blue, green and red respectively (let's just assume for now that the optics are optimized for the 320-1000nm range we are interested in here). The logic behind that was to increase the range of EM spectrum observed and bring out the electric blues in hot O-B stars and deep reds in relatively cooler K-M stars kinda like what Hubble does. That to me seems like an informative image, even though it might not contain the spectrally pure violet, cyan, yellow or orange colors. You know that when you look at the blue channel that's the information from 320-488nm, green shows 491-574nm, and everything from 575-1005nm is red. Obviously, the camera sensor's QE response (and the optics) do naturally cause a slope in effective QE of the system in U & I bands, which does help in somewhat achieving some distinction between the different regions of the spectrum by creating varied shades of blue or red. That to me, is a meaningful image.
After reading this thread, the idea of being able to capture the spectrally pure emissions in their true colors (the color that we "see" that wavelength in, not necessarily the object in space) did seem interesting. If I understand this correctly, the goal is to have HeI & NaI emissions appear yellow as our eye would see that wavelength and not red as they would appear if mapped to a square cutoff filter, and then likewise for other emission lines. Sounds great. But how do you expand this to outside of the visible range? You can even map U to violet/purple, but what about I? Let's say we limit ourselves to the visual spectrum. Looking at the Classic overlapping filters it seems like the HeI & NaI emissions still wont be yellow but rather orange. Wasn't our goal to see spectral yellow as yellow and not red? Is it okay if it is still not yellow but rather orange instead? I do want to learn more here cuz at this point I think that sure, color diversity would be great, but I still would not know what those colors represent because everything would be arbitrarily skewed to slightly different colors. So now I have an image that's more "colorful" but the colors have been somewhat contaminated.
Now as I'm reading another great thread "True color again" by loujost, I'm realising that honestly for visual spectrum there's nothing better than a modern mirrorless camera in faithfully capturing colors in a way that we see the world in. The moment we even move to an OSC "astro" camera, the lack of LPF filters, etc. make it shift away from how we see the world from our own eyes. Given that information, I think if one wants "True Color" they should go no further than a modern mirrorless camera (and I know even that is not 100% accurate "True color" but oh well). Now that we have that covered how do we choose which filters to go with for monochrome imaging? It brings me back again to the square cutoff UBVRI filters. At least there I know what the blue, green and red channels in the final image would represent.
This is where I am right now. I'm honestly more confused than I was before coming accross these insightful threads, but that is a good thing. All it means is that I know that I need to learn more. And therefore I ask you (and others) to chime in, I'd like to see what you guys think about this topic.