[Geckorian]

spawn rate seems low because the amount of mobs spawned has to be divided by the number of open chunks that they can spawn in. The more people on and spread out, the fewer mobs you will see in one area. This is way spawn towers are pretty useless on the server. On the plus side, the server has been up long enough that there are likely free to use mob farms for just about any mob you are looking for, just ask around in chat.