You do. Sabaton and Alestorm were classed as a double-headline gig when I saw them, although I think it's fair to say Sabaton were really the bigger act.Though you do get those rare cases where the two bands playing are at essentially equal levels of popularity. For instance, I recently saw Sabaton and Amon Amarth in Sydney, and (set length excluded) it was for all intents and purposes a double-headline gig. Great stuff
The commonest mismatch I see with metal gigs is pairing modern Kerrang-type metal with a more old school metal band, or pairing thrash with something like melodeath or symphonic metal. In the case of the thrash support acts, people turned up just for those bands and left before the main act came on. Which was great, because I could see the main band a lot better and all the pissed fighty arseholes were gone.
It's definitely hard to pin down, and I think they sometimes guess at what "the kids" are into these days* when they choose Maiden support, or fall back on old school/retro because they know that's likely to appeal to Maiden fans of a certain age. Personally I love the idea of Sabaton as Maiden support, but a lot of people find them too cheesy to bear. Ghost was a master stroke for the US TBOS tour, though. Just that tiny bit of controversy a la NOTB that accompanied Maiden's original rise in the US, plus a band that was growing in appeal in the US anyway.And what makes it even more complex is that "Maiden fans" engulfs a very large spectrum of people: some enjoyed Nightwish, some liked My Dying Bride, some were glad Queensrÿche opened for them (or Trivium, or Murderdolls, or Dream Theater, or Megadeth, or Helloween, or WASP...)... and none were "casting mistakes" as such, just that very diverse bands could fit the spot and be liked by a certain fraction of Maiden fans. There is no real focus, let alone when Bruce and Steve let their children open for them.
*Something I suspect Steve in particular is quite bad at.


