We haven't tried any servers in US, but Darvince has complained a bit about it, even though many US and Canada players don't experience the lag that he has complained about, making me think it's unlikely that it'll make much of a difference, in any case the distance between Arizona and Germany is about 5800 km, a distance that it would take light 0.02 seconds to travel, with the occasional chest lag lasting for seconds and things like that I doubt that is the important thing here. The same argument could be used to say it really doesn't matter if I host it in USA or Europe the other way around. It probably doesn't matter much. It would be a bit of a mess to move server again though unless we upgrade if the location isn't important.
Why do you want it in US smjjames?