maybe i'm off, but i always thought that a reversed gate was like a ducker, where you have a noise gate that only opens when the level of the control signal falls below a certain level, and closes when it rises above it. you could use something like that for an automatic "talk over" feature, for example, where the music is muted everytime you use the mic, and returns to normal when you stop, or to make a reverb or echo effect come in during the break, but stay quiet during the busy parts.