Mixing a whole slew of similar instruments together has always presented some problems for me. The last time I attempted it the only EQ I had was a basic non dynamic EQ.
 
If I were doing a wall of guitars now I would use Neutron or a similar plug in with the ability to compare EQ's of multiple tracks and  allow you to see it visually and move the EQ freq. around to avoid those inevitable clashes.
Maybe use a dynamic EQ to tame unruly mids. Look at an analyzer to see where all the energy is in the track. Bass doesn't cut, the mids do, If the audio lined up I would try to match the mid frequency pluck of the bass guitar to the higher guitar parts. If you have both of those working in tandem you might get the best of both worlds. Cut the mud out of the bass, maybe duck the bass from the drum track.
 
No two mixes are ever identical, but this is where I would start. Little things could muck it up fast, like to much gain in the busses, too much or the wrong kind of compression on individual tracks. I could easily see one of these large metal mixes taking all day and then some to get right. I feel fer ya.