I would disagree with the comment about Clive. I've always found Burr to be inferior drummer to Nicko, and I'm not usually one to care about technicality. I just think that Clive hides his lesser skill under fast but simple drumpatterns, while Nicko does much more complex stuff. Nicko also adds his own touches to the songs (also Clive-era) and he's a more recognisable drummer. For example, on the studio version vs. LAD version, compare the point just before 3:10, before Bruce starts singing "As the guards march me out to the courtyard..." Nice extra by Nicko that isn't done by Clive. Clive is bidedal, but Nicko is a friggin' octopus. And don't make me mention his double-bass sounding single bass.
I'll admit though that I know absolutely nothing about drumming or music in general, so sorry if this sounds horribly untechnical or otherwise incomprehensible.
Oh, and I've personally never liked Killers. It has some fantastic songs (Killers, Wrathchild, Murders in the Rue Morgue) but the rest seem pretty mediocre to me. But it could be I've never given the album enough of a chance, as I do like the first album.
As for good +10 minute songs from other bands, Iced Earth and Helloween spring to mind. Iced Earth has Dante's Inferno and the excellent Gettysburg trilogy (which I sometimes consider to be one song). Helloween has King for a 1000 Years, Halloween, Keeper of the Seven Keys, etc. All good songs. Compared to this, Maiden has surprisingly few long songs. Only Sign of the Cross and Rime are over 10 minutes in the studio (Paschendale live is longer because of the intro). Near 10 minutes are a lot of songs, though: The Legacy, For the Greater Good of God, Seventh Son of a Seventh Son, The Angel and the Gambler, Dream of Mirrors... Old Metallica has some 9-minute ones too, mainly from their fourth album: ...And Justice for All, To Live is to Die, and Call of Ktulu.
Maiden might have been one of the first metal bands to make really longs songs, but they aren't the only ones
