I spent most of the past week going through each arena and updating the visual appearance. I decided to go to a more sleek, shiny look which is greatly helped by a new reflection shader (called Candela). I removed most of the metallic / quasi-realistic textures.
I'm pretty happy with the new direction, and think it closely resembles what the final game is going to look like. But please let me know what you think!
I also added a few 'ball railings' to a few levels' platforms, which should help keep stray dodgeballs elevated and therefore spread out players a bit more.