The con of this option is that if it is set too low there may be some false positive. Thats why we have selected it above the normal range used by other populat hosts like Godaddy, Blue host etc. Read full comparison of our hardware resource with other hosts here.
The picture above shows an ip being blocked by the ConfigServer Firewall. The ip had 244 connection and crossed the 150 limit. This happens so fast and server is continuously monitoring connections of all the ips. When the sever detected that a certain ip was above the threshold it blocked the ip permanently and notified us using an email.