The answer shouldn't really matter since the club world doesn't reflect the real world. Drunk people dancing to song doesn't mean it's going to be remembered. Do you really think that this song is going to be a piece of pop history more than Born this Way? Whether or not overall it sold more, it didn't have the same media coverage or awareness that Born this Way had.
Tell 'em!
But really, though, congrats to will.i.am and Britney on their success.
IFPI isn't that reliable, and they messed up quite a few times. Didn't some Paramore single appear on the list selling over 6m out of nowhere when it wasn't even a big hit?
Crushcrushcrush was huge in Asia. Don't underestimate the Oriental power