In my experience, sticky sessions open a whole new can of worms. With proxies and VLAN, it's very easy to have an extremely unbalanced load if you use naive IP-

In my experience, sticky sessions open a whole new can of worms. With proxies and VLAN, it's very easy to have an extremely unbalanced load if you use naive IP-based balancing. If one of the servers becomes a "hot spot", adding more servers won't immediately remove the load from that. And when a server dies, the sessions in that server are lost. These problems can be mitigated with an in-memory distributed database overlaid on top of your cluster, but that opens its own can of worms...