You will run into trouble with bigger diaghram mics. I guess you could compress those channels, I never have. I rely on my exquisitely musical ear and instinctive riding of the faders. Seriously, you need to be able to listen and move the mics and the C-ducer strips around until you get the most even coverage possible. Either device will naturally accentuate the notes closest to it.
Pianos are what separate the adults from the cubs.
There was a night with Dr. John opening for the Neville Brothers, when the venue guy started his mix, then the Nevilles' guy got involved, and finally the systems guy put them both to shame. He could really work that parametric. You can also dig yourself into a very ugly hole that way if you don't analytically understand the piano's frequencies. Listen to a Diana Krall record. Al Schmitt is the man.