They are also impeccably behaved.

I still see a lot of cultural issues, but I agree that they are well educated on average.

Act like Americans, I think they do not, but no they're probably not out in the street murdering each other. For the most part, you'll notice that immigrants from far, far overseas aren't. It is the more local immigrants that seem to be the biggest criminals. Perhaps due to self selection during the long journey, as you were hinting at.

I think the same thing about Chinese to an extent. All the really dull ones are still in China.