I mentioned this the other day in chat. I believe the reasoning behind the "persuasion" for EU to play EU and not NA (and vice versa) is because of the way the combat is. Other MMO's have had an easier job with the "auto-targeting" or tab targeting features where as long as you have a connection and are in Line of Sight, your stuff will activate and hit/miss as per a formula. With WS's targeting methods of actual positioning, high ping is a real detriment / concern for this more active style of combat. Nothing is worse than seeing a mob, attacking it, only for things to miss because the servers are saying one thing and you're seeing the "delay".