Efficient way to randomly pick a color channel in materials?

[Travis]

Sometimes that has to be the trade off. These are things on the screen for less than 0.3 seconds, so I doubt anyone but a vfx artist playing in slow motion will notice

[Orson]

This is I how I make Texture Channel Selector :
This way You can easily select one channel or get two with (1,1,0,0) for exemple