Have you ever observed what your switcher does when the load current goes from 20% of rated current to 80% of rated current? If so, what did you observe?
yes, I have and nothing much

Have you ever observed what your linear does when the load current goes from 20% of rated current to 80% of rated current? If so, what did you observe?

I suspect that sort of thing happens pretty often in your bus-display environment, so I imagine you've looked at it quite a bit. Of course, it's probably not particularly important, since your display can probably recover within a few milliseconds if the supply drops out. Nevertheless, you've probably seen the worst-case.
since a color display have one 'dose' of 1/2ms the maximum allowable 'dip below min' is in the 10us range for the LED supply. Of course, for the logic supply it is zero.

Erik

dose: (could not find a better name) one way to create color is to display one display for 4ms, another display for 2ms, another display for 1ms, another display for 1/2ms. This gives 15 possible intensities each for red, green and blue