Something I tried out with my new Pod X3

Personally I wouldn't recommend putting different tones on the left and right sides. I guess it's a matter of taste, but I've always thought mixes with such arrangement sound unbalanced. I always go with two different tones on 100% and 80% on the same side.

don't mean a "very" different tone on each side. I just mean one more "scooped" regarding the amp settings and the other one more "mid-rangey" (the same settings as the scooped but with less bass, less treble, and more mids)

I'm not sure about this but on the Slipknot Iowa album both sides have a very different guitar tone. One is darker, the other one is brighter. It doesn't sound unbalanced to me, and when one guitar is playing and the second guitar is entering on the same riff it sounds HUGE (listen to the beginning of "the heretic anthem" track and you will hear).
Anyway my example may be not so great since :

-they both have a badass guitar tone
-the production is awesome
-i don't know if it's quad tracked or just dual tracked
-i don't know if they used the same amp just with a cooped setting and a mid rangey setting. The difference in tone and the fact that they complement really well may be due to : different guitars and different pup's, different amps (one with more low mids and the other one woth more hi mids maybe), etc
 
Actually I'm not that satisfied... I think I'll do the guitars all over again. I want the sound to be more aggressive and in your face. Any suggestions?

I think your tone is decent even if not badass, but don't expect a miracle it's still a POD (personally i've always heard decent tones from POD that work for demos but never been "impressed" by those... they have a voicing and character i don't like) and can't compete with a real badass amp a la DR, 5150, Powerball...

But still you can improve it i guess, the POD users can give you some tips i guess.