It would be nice, if the viewport representation of the RayswitcherMtl would be drawn from the material in the direct Override slot,instead of the GI slot.
Logic being, that what you put in directly visible should be the thing shown in the viewport.
I use Rayswitcher constantly, often with a corona light mtl in GI override slot, but a selfillum Corona mtl in direct.
Thus all these materials appear as black in the viewport, which is not desirable.