I've only seen Metallica once, in 94 or 95. Suicidal Tendencies, Rob Halford's Fight and... Candlebox (subbing for Alice in Chains back when they had to stop touring due to Layne's drug problems) opened for them. Wonderful show from all involved. And absolutely the best mosh pits I've ever been a part of (and a nonstop, all day affair, at that). God damn was I young and full of energy back then. Any tinnitus I might currently experience can probably be directly attributed to Halford. Fuck, that guy is unbelievably fucking loud.
An odd thing happened though, in the middle of Jason's bass solo. He abruptly stopped playing after a minute or so and ran off stage, as if upset. A minute later the rest of the band, minus Jason, came back out and started up the next song of the set. When James wasn't singing, he was looking off stage and screaming at someone pretty angrily. Jason appeared a few minutes later.
The articles I read about the show afterwards mentioned all the wheelchair-bound fans being lifted up and tossed around during One, but there was no mention of this particular incident with Jason. A nosey part of me has always wondered what had transpired, but I think I more or less got my answer when Jason left the band six or seven years later.
Anyway, that bit aside, the whole day ranks right up there with my favorite concerts of all time (with a couple Oingo Boingo Halloween shows and a later Suicidal Tendencies, System of a Down, and Snot ticket a few years later).
And based on recent live performances I've seen streamed, Metallica is playing much tighter now than they were ten to fifteen years ago around the late Load/reload & early St. Anger eras (a couple particularly difficult Kirk solos not withstanding). They're seriously kicking ass live right now. Brush up on the new album, I read something recently where they're squeezing five or so songs from it into the setlist for this tour (no word on Spit out the Bone though).
I only know one Volbeat song, the Warrior one from the latest album. They sound like they'll be a great opener. I don't know much about Avenged Sevenfold other than their reimagining of Sad But True.