As someone who's worked with the unreal 3 engine in a professional capacity I can tell you that there's a fair bit about those systems that are hard-coded. The

As someone who's worked with the unreal 3 engine in a professional capacity I can tell you that there's a fair bit about those systems that are hard-coded. They just look very nice from a 1000ft perspective. There are parts of UE(like the material editor) which are very modular but the networking stack is not one of them. This is not a knock against UE3, more that things are more complex then they first look.