Well, no doubt my vote is against. Here are the reasons why:
I know quite a few players from other servers outside the ES that gives them lag, to such an extent that even the same ones from your server complain about them.
A separation will not solve the problem of latency, because as I mentioned before, it will still not solve the problem of high ping.
A good measure would undoubtedly be to force the player in PvE that if he has 300 ping or higher he can not use the grouping, because even a Latin with 0.5 MB network will not exceed them. The same for PvP, that the pairing does not allow you to play until your network improves, even in practice PvP. In case a player has an increased ping of more than 300, a warning appears on screen that his ping is above the established limit and that if he doesn't stabilize it in 15 seconds he will be transported to the village.
People here misunderstand the situation, it is very different the Delay that is treatable (As I mentioned earlier with less than 300 ping, you can do xdrops without problems or play) to ping abuse, which is the real problem of Elsword.
I'm still surprised that at this point you still think that ES = Lag. Since it has already been seen on many occasions that in all servers there is abuse of ping (Which players are aware of and use it for the same reason.).
Just put a ping limit system is enough, because with 300 ping or less is quite playable and does not reach the degree of ''frustrate'' players. And stop naming IP ban, that personally that would only make those players use VPN and have a ping too high, making them affect 100% of the game experience.
I'm sorry if I don't write well in English, but I hope the point is understood.