I prefer to have larger capacity and more stable server than have another one..
the reason is simple, alot online game out there makes new server when their game become popular, then end up merging them and suddenly lose alot of players.
ofc many people will try the new one, and spend more real money for membership and other stuffs.
but, from what i see alot of games end up merging their server when player start to go away, and end up with closing server, because when they merging it so much problem appear mainly about unstable economic system after the merging which drive player away from the game.