Map size restrictions for VR multiplayer?

I’m aware of the general restrictions on a single map size for multiplayer open world games in UE4 (I believe it’s currently at 20,000 x 20,000 units since the update. However, I’m curious to know what the workable (i.e. doesn’t slow down completely) max map size is for a VR multiplayer; an exploration game or something similar?

We’ve built a 10,000 x 10,000 units single map that seems to work so far (although much of the space is currently empty terrain, so it may become a problem as it gets filled with more content) and any additional areas of the world added in future will be on seperate servers. Has anyone else experimented with large map size in VR? I’ve seen other VR MMO style games that appear to use a large open world map successfully (OrbusVR, etc), although I have no idea if they use UE4 or not.