Interesting Plugin, Feels like it lacks some tricks... Like, Would love to switch the filter section to just an internal sidechain circuit... that way you could manipulate the transient response without having to colour the output with the filtering. The GUI is very neat and clean, which i appreciate a lot... Am keen to see if this matures into something a little more surgical... Will definitely keep an eye out. :).
It's a bit more complex, but it's basically the length of the detection ramp, i.e. how quickly it will react to the detected change. And yes, you can say that it is an arbitrary percentage of a some fixed amount.