As I have been working with this side by side with the stereo mixes, I find that there is something different in maybe 1 out of 5 scenes on average - added, missing, or just different background sfx / different foley effects (footsteps- enviornmental sounds) / slight offsets in dialogue positioning / occasional alternate takes on select lines of dialogue - in short, lots of stuff that has gone undocumented. It has actually may the synching process far more complex than I had anticipated.