Agree with Gijsbert – worst nightmare is to have some automatic processes into your signal chain and get heart attack when unit figures something out for you. Have seen some of these in action, funny for audience and terrible for FOH guy. Let me describe this- you get feedback at 3k5, it gets louder and after 0.5 … 1 sec. when everyone have heard it, unit comes in and puts some -5 dB notch, this freq goes down, talent asks for more input (as some information has gone with the notch) and we get next freq. And then unit runs out of filters, then it takes oldest filter and release it to use for next freq. And then everything starts from beginning. Not going to tell about long notes on electric guitar… 
My oppinion is to ring out monitors, step back in level couple dB and save ones nerves.
ddff
