Van Canto I would love to see them at PP

I'm not sure it would be THAT hard to manage the mics and the sound for a good crew like Glenn's.
I had an acapella group perform on 'my' stage at Dragon*Con this past year and it came off really well....with one sound-tech and a pair of Bose PA towers.
 
I think that just about anything can be cool if the song quality is good, and Van Canto can write. I imagine the songs would be even better with full instrumentation. Maybe if they get big enough you'll start to see other metal bands do cover versions of Van canto songs with the gimmick of using instruments.