After a quick read through of the thread, I didn't notice anyone mentioning Free Bird. There's a section about a non-standard tuning for at least one of the guitars:
http://en.wikipedia.org/wiki/Free_Bird#Slide_guitar
Namely, the B string was tuned down to a G. I don't own a pro guitar, but I experimented with my acoustic guitar, following along with a YouTube video of the chart, and IIRC (at least parts of) the solo sounded wrong if played with a standard tuning, but correcting for the tuning down made it okay.
Someone with actual guitar experience could maybe verify.