Bartolo wrote:I've seen around 3500 on the third day of the PvE server... but never again

Well that's very obvious. At server start tons of people just want to experience the "atmosphere" of a new server with hundreds or thousands of people in the starting zones. They make it to level 5 or level 10 and then stop playing again. Obviously cannot count that as "real" server population.
I started playing on the PvE server in November and I think I can say I see a constant healthy development of the population. You also have to keep in mind, that there is very little content available at the moment and I'm sure, further released content will attract more people. Nonetheless I don't think we need a much bigger population to be honest. Maybe a slight increase and a more equal A:H ratio. Other than that, I'm very happy with the current state of the server and the blizzlike feeling here.