I went to a massive at the Forum a couple of years ago, and they divided the arena in half with curtains, and had two stages back to back. Surprisingly there wasn't much sound bleed except when you were between both stages.
Like everyone freaks about its in the ghetto, cars get stolen etc etc. I have never had anything happen in all the times I have gone to the Forum, parked my car in what most of you guys would consider a sketchy neighborhood and come back unscathed. I am sure they will have double the amount of police at this thing compared to what they had at Hard Halloween.