After watching the Petrucci video where he plays his new amp, and hearing him gush about the IIC+, I thought I'd have a go at playing around with the mode on my V:25. And on the back of the question of how well these 2 channel amps can do for rhythm and lead on one channel, and keeping one free for a clean sound, I tried to do something with just that one mode and use it for both rhythm and lead. Sean suggested having the EQ off for rhythm, and then engaging it for leads, or vice versa, but I couldn't find anything that I liked the sound of in both states. Plus I'm lazy and just like using the same for both.
I'm far from a tone snob and don't claim to get good tones (I don't even really care about that shit, I generally just find something usable and live with it), so maybe I'm not the best person to judge this. But to my ignorant ears, this sound is ok for both rhythm and lead.