I like the "core four" concept but I think 2 sets without a lead instrument would be too much. The way I see it, have the 4 do the first set, then, for th second set, bring Barraco out on keys and kindly ask Herring if he'd like to come back to the table. If he declines than seek out Matt Hartle and let him have some fun.
Rob seems to have so much fun in that seat and he'd be able to help with the vocals. Watching him belt out Doin that Rag really brings the energy level up.
As for Herring I always thought he was lacking something when it came to pulling the band along with ideas. You know, everyone kinda puts in there twists and turns but it always seemed to me that he would just kind of follow everyone else...and if he did get to far out in front he didn't know where to go (my two cents). However, the last tour that he did, it seemed like he was really getting comfortable and my sour oppinion was slowly doing a 180.
Wouldn't you know, he decides to pursue other dreams.
At the very least: no Warren, Trey, Molo (he's good but would much rather have Bill & Mickey), Joan, Robinson, or Campbell.
"Stupid music makes people do stupid things"--Anthony From Bonnaroo