Hey Everyone while playing around with Eevee and shaders today I noticed this about the mix shader when plugged into the roughness of the metallic material output. That being that it can be used a strength amount to dial a single input by. By adjusting the factor of the first 2 mix shaders I was able to come up with a variety of different looks etc to Suzanne. Not sure if this is how they are supposed to work as I always thought that it mixed 2 together. and made no difference to a single input. Or if it does the same in 2.79 or 2.78C etc.

Incantrix