Knowing how a human brain works, the realm statistics might be the biggest problem for Warmane. If one sees the realm he intended to play on has low numbers (Cata / MoP expansion), he might think twice if he's gonna invest time on the realm.
Look what has happened to Neltharion - players seen low numbers, so they left the realm.
I suggest to show only total amount of players (sum of all realms) AND a word-representation for each realm (population: average, medium, high, full) - avoid the word "low" for obvious reasons.
Icecrown: Full
Outland: Medium
Lordaeron
Blackrock
Frostwolf
Doesn't look good, does it? Considering that the Who list does not work in-game, if Warmane removes pop count, it would be an instant sign that the server is losing population and wants to hide it.