Nah, there's no argument from me, anyway. Channel 2 on the Mark IV is a mid-gain channel, not a replacement for Channel 3. I always set mine like a two channel amp (clean and high-gain on 1 and 3) and could boost for leads if necessary. Channel 2 was fine for mid-gain stuff (lighter rock, etc.), but it's not intended to be a heavy metal rhythm sound. Boosted, maybe.
I mostly ran my Mark IV to the Petrucci spec. Altered to taste and for my gear and playing, obviously, but with that same priority on channels 1 and 3 when tweaking.