An acoustic set would be interesting. But what could they play?
I'd think they would do a version of "Wither" that is a mix between the piano/vocals only version and the album version, with acoustic guitar thrown on top.
Also, "The Answer Lies Within", "I Walk Beside You", "Vacant", "Disappear" (!!!), and maybe some old FII-era songs that haven't been played in awhile. Maybe "Solitary Shell" and "Goodnight Kiss"? It'd be hard to do some of their longer, and/or heavier songs in such a format... but if they had to pick an epic, I'd say maybe "Trial Of Tears". How funny would it be if they pulled out "Space-Dye Vest"?
-Marc.