Well, I expect that such an action might throw off the balance for other patches. For example, the dip @ 640 nm is not so deep in the ‘white 9.5 (0.05 D)’-patch (18) spectrum:
Compare that dip with the patch 20 dip plotted above. You can either adjust for the .44 D or the 0.05 D patch, but not both.
Given, that slight variation of the color balance (in this case related to different levels of grey) might not be noticable at all - I do not know at the moment. That’s actually what I want to find out: what is the risk associated with narrowband scanning (trying to achieve something like “maximal color separation”) vs broadband scanning (simulating in a way the broadly tuned visual system of human observers). For general reflective spectra (printed color checkers), I think I already showed here that using narrowband illumination is not so good in terms of color fidelity. My current adventure is to check whether the same holds for transmissive spectra constrained to be composed from only three components (the three film dyes). I expect that the broad dye spectra help here with narrowband scanning. Will be interesting to compare different scanning setups. That is: broad- vs narrowband illumination, optimized camera matrices vs scientific tuning file matrices, etc. But that will take a while until this is implemented…