@Myke - The different tuning is probably what causes it. Bands switch guitars out all the time, so I don't know why Nevermore doesn't do it.
There are only a few songs (to my knowledge) that have never been played live:
Insignificant (they played all of Dead Heart on their headlining tours when the CD came out, minus this one... which bugs me since it's one of my favorite Nevermore songs)
42147 (Warrel told me that they HAVE played it before, but him telling me that is the only evidence of it happening. I have quite a few bootlegs from the Politics tours, and it never popped up)
Sorrowed Man (I could be wrong with this one)
Psalm of Lydia
Seed Awakening
most of the new CD, probably some more from Godless. not sure.
What about Chances Three?