Most images were rejected because the performers had a microphone or some other object covering part of their face! How rude! LOL
1. Some of my lenses had a problem locking focus on the performer's faces.
I only brought three lenses, the 35mm 2.0 IS, the 50mm 1.2L and the 85mm 1.8, since I knew I would be able stand at the edge of the stage.
2. I almost always shot wide open.
I am not professional either but shoot few of these a year, sometimes in low light, sometimes not.
I find shooting concert and boxing to be very similar. I do a lot of waiting for the moment.
I chase for 3 things:
1 - the right light: I usually don't shoot in magenta or green or red - shoot mainly yellow and I really wait for it. I need this kind of shoot for any member of the band and I prefer taking those when he/she doesn't move - these are image quality shots (1/80-100s)
2 - story: I chase for their reaction - here I go for high ISO and faster shutter speed (1/250s). I don't care about the light, I just need the right reaction.
3 - For him/her to look at me (1/100s).
I use only prime (that's because I don't own a zoom, I only recently bought 100-400 II and haven't had the chance to try it). My preference is 85mm at 1.2 for 1, 200mm 2.8 for 2 and 135mm 2.0 for 3. I will soon incorporate wide (or super wide) angle in my arsenal.
I always start with 1 then 2 then 3. Always wide open. The distance gives enough dof.
I never focus on their face, I focus on their chest and when really, really needed I use a flash trigger with assist beam.
I always shoot burst of 3 at least, sometimes 4 or even 5. My configuration is shoot first then focus, and for the second shot: focus first then shoot.
Usually, the 2nd click is the keeper, so I pre-shoot.
The key for me is waiting for the right moment. I really really pay attention to that and can go 3-4min without taking any shot until I get what I want, then I burst.
When I am the main photog, I ask for permission to use flash and when allowed I bounce it from the other end of the room (einstein) using, usually, a lighting ratio of 35-50% flash.
When dealing with a very famous artist, I rent the 200 2.0, but it is quite heavy for a concert, hand-held.