If I can play the game from Australia on a JP server you guys should be able to handle playing on a server located on the same continent. There was no way that no one was going to be at least slightly negatively effected by this move and frankly there are a lot of factors that would effect performance beyond physical distance. They specifically chose a location with reliable and well developed internet infrastructure according to the live letter.

As I said, if my FC can raid Savage Alex with AU ping then you guys in NA should be fine. Frankly give it a month or two and you will probably be used to the change and barely notice it anymore.