Excluding 1000 keys that grey order leaders have and excluding all the alts that other, normal non-cheating players have, I would put the player-count at about 600 to 700 if you take into account server activity and day/night shift players, then from personal experience I would say that my 600-700 guess seems about right.
Also of note, I am drunk, so maybe not thinking straight right now.
cept that about grey ordr, that is ofc true.