If you look at the setlist from the rehearsal show for the Elevation tour, it didn't differ dramatically from the actual first night, 20 songs for the rehearsal, 22 from the opening night (11 O'Clock Tick Tock being played at the rehearsal and not on opening night, I Will Follow, The Sweetest Thing, and Streets appearing on opening night but not during the rehearsal). With the exception of one of two song placement shifts, what you saw during the rehearsal was what you got on opening night. While the first three shows had some variations, the fourth show was the first show to repeat a setlist from an earlier gig. And the first 9 songs from that rehearsal show were also played in the exact order on opening night (compared to the foursome from Popmart's rehearsal that appeared in order on opening night).
So if this holds true, then my pick of Vertigo for the opener goes down the drain. When you look at it, either Vertigo or COBL are great show openers ("Hello Hello" and "Oh you look so beautiful tonight"...and maybe it's even better to have a majestic start this time as opposed to a bombastic one...I'll take either though
).
Opening night's always a bit rough. I was at Springsteen's opener in Jersey on the Rising tour and it was pretty haggard at best, if not impassioned. The tweaks came right after for a more cohesive performance on that "Barnstorming" tour of his. Even though he was literally repeating setlists song for song until later in that month, the show itself was already polished, fine tuned machine within a few shows' time.
I think you opening nighters have the advantage of seeing the show for the very first time. That alone is awesom. Given U2's history, give 'em a few shows as well. Once they become confident as to how the older stuff can be integrated with the new, this tour's gonna be outstanding.
