I have been using a roll-off fairly frequently, especially in smaller venues with hyperactive subwoofers. Even with a mild roll-off, the waveform drops down to barely above -18db, meaning to me, that the bulk of the sound being picked up, and affecting the setting of our levels, is coming from the low end. I find that it can dramatically clear up boomy recordings in acoustically challenged rooms as well. I usually copy and paste sections from a few songs onto a new page in SF and then try different settings, as they process much quicker than the entire file. Once I figure out what I like, I go back and apply it to the entire file.