They even performed at Werchter a few years ago and I read that some of those metal group bandmembers looked quite miffed (what on earth was a girls choir doing on this festival??), but when the 2 brothers (1 pianoplayer and 1 conductor) came on stage with thair harem of about 150 young girls they looked quite jealous (story told by one the Kolacny bros)
I also remember reading an interview with Daniel Lanois.
He was performing at the same event as Scala.
Scala was rehearsing WOWY backstage and the interviewer mentioned that he looked funny, recognizing something very familiar (could have been at the same Werchter gig, not sure though)