I was in section 128. I agree that the sound was really good for both Megadeth and Slayer (we missed Testament). But Dave's voice was really off early on. I've noticed this previous 2 times I had seen Megadeth before this (Sonisphere in the theatre, and in Scranton, PA in the spring). I think age might just be kicking in on his vocals. His voice did start to sound better on later into the set and especially when he stuck to more the growling style of singing. Musically they were great. Dead on and the solos were killer. This Megadeth lineup is proving out to be their best(IMO).
Slayer of course was awesome. 'nuff said. Not sure I could ever complain about what songs they choose to play. Loved that they played the entire "Seasons..." as I loved seeing them play the entire "Reign..." a few years ago. I could see them do this for "South..." and "God..." and be just as happy.