Hey dude. I listened to all of the mixes.
First of all, cool tune. Very creepy old school Morbid Angel sort of vibe. You know what's up with the drums so no need to go there.
The guitars are pretty muddy. Look at doing a cut somewhere around 250 to 300 hz. That's where most of your mud seems to be.
Have you ever gotten ahold of a decent parametric eq plugin? You could try setting one band to about a 10 db cut and then sweeping the frequency until that muddy stuff disappears just to find the right frequency range, and then adjust the amount of cut to suit. Of course some of that mud is reminiscent of old school death metal so I could see why you would want a little bit of that "woofy" guitar sound.
Just playing this thing in my windows media player and using the horrible eq that it has, I cut out some 250 hz and boosted a little 1000 hz and the guitars got way clearer. There's a good starting point!
Is this with the V-Amp? When you layer your tracks, you might try doing two of the tracks with a different sound if you're not doing that already. Maybe a brighter sound with the low end turned down quite a bit. Two tracks for definition and two tracks for heaviness.