I have a cheap Behringer noise suppressor (an old model now out of
production). Its adaptive notch filters can be "freezed" once they are set
for the particular application, so they don't move around during the
performance. It saved my day several times with an amped acoustic guitar
that simply wouldn't behave nicely. Yes, of course it changes the sound,
but the extra headroom can be HUGE: not just a couple of dBs, but the
difference between having to keep the guitar almost completely unamplified
and hearing it clearly in the mix.
I can't see why something similar wouldn't be attainable with a plugin.
-- Emanuele Rusconi