The impression I get is that they aren't really known at all in the US yet. They are pretty big in the UK - I saw them a couple of years ago at Reading Festival a couple slots before Metallica and they smashed it.
Really looking forward to this pack, although can't help feeling a five pack would've been perfect. Figure It Out, Little Monster, Come On Over, Out Of The Black, Loose Change - job done!
They actually charted higher in the US than in the UK.