And their relevancy is only increasing; releasing MM was a great move to start transitioning into music that will appeal beyond teen girls and gays. I know so many adults (male and female, gay and straight alike) who like or love 1D right now.
I'd say 7. Their fan base are just too loud that you'd think there are more of them than there is actually is. You'd think they'd be outselling everybody by how active their fans are on social networking sites.
A few months ago I would have said 6 because despite their success the GP didn't use them a lot nor did radio. 'SOML' changed that in terms of radio but I feel there is still room for improvement, hence my 8.
Tours and albums are always big, singles are so-so... some of them are successful, some of them start off well and then free fall, luckily SoML has been doing great.