i run a macro for this, but instead of working on the volume curve, it does indeed slice the actual clip on either side [of the selected range], and brings down the volume (essentially the de-breather you’re talking about). the thing i find more reliable about this approach is that i found automation curves are less precise, and, at least with my RME interface, tend to produce slightly different results based on the buffer-length of the driver, whereas direct editing of the clip / waveform seems to be sample-accurate in cubase.