I like the sharp shadows on the faces and the determination of the brothers. It looks like you managed to use the dynamic range of the sensor to the max without really disturbing overexposure. Technically interesting.
Faces! Sharp focus! Finally musician/concert images with faces in focus. To bad the guitar stem cuts through the head, but I'm happy to see faces. Might see if you can pull down the highlights/white-level a little.
Shooting musicians on stage without flash is hard. You've done a great job here. I have one problem with it though. That's the gray thing in the corner, I'm guessing it's a microphone. It is kinda distracting. 8