My band used autotune once, for a single note that our singer just couldn't seem to hit. It still bugs me everytime I hear the song, 'cause I can clearly hear that just this ONE note sounds artificial. I have never asked around to see if anyone else cares, or notices it at all, though. The funny thing is that it is in the verse of the song, so the note comes up more than once, but only one of them was a problem for him. Seriously, we did billions of takes trying to get it right, before we gave up.
On a more related note, I listened to Emptiness Unobstructed today. I have promised myself not to listen to the album until its release date, but I have been curious to hear this song since Warrel posted that recording of him recording the chorus of it on his twitter, and I just couldn't wait any longer.
Great song! Possibly a personal Nevermore Top Ten candidate. Every little bit of the vocals is just awesome. The solo is ok, too... not great, though.