A mate of mine records DnB Arena events for their website - says it's a fairly complicated job as you've got to think about the MC's Mic, the Mixer and sometimes ambient mics in the room - the really complicated part is getting the balance of all these sounding right, which is why so often tapepacks sound whack...
Also what's a bit of a pain is that what sounds good at the venue won't necessarily sound good on the recording, so you're constantly battling trying to get a good balance... He says some of the MC's are more helpful than others and will check in with him to make sure the recording levels are good, wheras others are more focused on the night and completely ignore him!