I volunteered to shot a cabaret concert held recently by my local High School at an Elementary School. Lighting and, accordingly, white balance was a horror story. Ambient lighting was a mixture of tungston and fluorescent lights and a single spotlight was used to highlight the performers, moving around during the performance.
I used the 5D Mark II and 70-200mm f.2.8L USM lens as I needed to be behind or on the side of the audience sitting at tables. There was no room at all to be in front of the audience.
Here's a shot that shows the general layout of the event.
I had to shoot wide open at f/2.8 using ISO 3200. Shutter speeds ranged from 1/30 sec. to 1/180 sec. depending on how close I was zoomed in to lighted subjects. I used a monopod since my 70-200mm zoom is not image stabilized.
Here are four representative shots. The white shirts on the guys seemed to make those scenes more striking that the all black outfits of the girls.
You can view all of the photos from the shoot here.