I just want to know with kill dry on, how does the function of the knobs change. You answered one: the mix knob becomes an instensity function. I am assuming the output knob simply increases the level of the wet signal. If I am running the box in a parallel effects loop, then increasing the level of the output would add more effect to the dry signal. 

In the end, but knobs would do the same thing: increase the intensity of the effect, but one would do it without increase the output level.