I am still just using the map loading approach. Recently we have been trying to get map loading as seamless as possible by using World Composition to load the surrounding areas, but the basis of this system is still just client travel from server to server. So there will always be a short load time between map transfers (about 2 seconds).
From what I have read, the approach you outlined that uses two network connections seems to be the most common approach to solving seamless server transfer, but that sort of thing is going to be a lot bigger project and probably isn’t something most indie UE4 dev’s are going to be able to afford.
I may look into something like that in the future, but right now I am focusing on finishing all of the management tools for the current system I have.