I see this post is too late
I see this post is too late for your concert but generally I'd say you should you spot meter in this situation as long as you know you can aim the camera directory on the stage/where the light is. If you aim slightly off the stage and the center of what the camera sees is actually a dark spot, the stage will be very overexposed.
If your far away from the stage and have an LCD BacPac to help you center the stage in the shot, then go for Spot Metering. If your close to the stage and aiming isnt going to be an issue, then don't use spot.
The other thing to think about is framerate. The lower the framerate, the more light will hit the sensor every recorded frame.
I'd would not go over 30FPS for low light situations.