It's one of the great unknowns.
The first Euro-LOTRO 64-bit server Orcrist ended up being not just swamped but overran, in that more players wanted to log in than the server could handle.
SSG have no doubt learned from that particular disaster ; but the truth is that nobody can possibly predict the real impact of how many inactive players will return to the game for the 64-bit, exactly how many tertiary toons on secondary accounts there actually are, and so on and so forth.
I personally think they'll be forced to open a second EU server -- because it's not just players in Europe itself but those across all of Eurasia (including the Koreans), Africa, and Australia who might prefer Amsterdam to Las Vegas -- but then I could be wrong about that as these are all still complete unknowns.
If they ARE forced to open a second EU server, well I DO very much hope that turnaround will be quicker for DDO than it was for LOTRO ...
OTOH I'd guess that the three US servers will be enough.
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BTW as to my personal latency ; well I am in a very unusual situation, in that I am on the French Riviera except with a pretty much direct internet connection to Florida, so that latency is pretty much identical for me whether it's New Jersey, Las Vegas, or Amsterdam. But I'm still moving everything to Moonsea, except that I'll put most of my overflow into Cormyr, and assure a presence on both Thrane and Shadowdale ...
