I use 2 outs from my rmbp all the time. I use 1 out for fullscreen from mix emergency, and the second out for resolume. I run a syphon client in resolute that receives ME's signal, and when nothing else needs to be shown it just shows the full screen output from ME, but if I need to show images or videos I can just fade out the layer ME is on to reveal something else. Since I have the first output already fullscreen from ME, than some of the displays still have ME's output on it