It would still be nice to have displacement that works like vray's - apply and forget about it, no smoothing groups, geometry modification e.t.c.
I could show you like 50 threads at CGArchitect on Vray's section where people ask the very same question about the same problem, and have been doing so for...past 10 years.
It's endless cycle where people become desperate and everyone gives them only one piece of advice.
So no. It works the very same way only with more (and very nifty) controls. Vray just also offers additional 2 modes (simple SubD and excellent 2D Texture space disp). Same protocol, people just don't know how to displace in general or
don't understand how their geometry behaves in render time. There is the option to force "continual edges" but it's not one-click saver for all cases.
Ok, here is proper workflow : // Renderer agnostic - I use the same workflow in Vray, Maxwell, and Corona. There is no difference, it's still 3dsMax Geometry.
1: Basic wall blockout.
2:
Chamfer the corners (using QuadChamfer plugin for example) // Quite bit suitable than direct SubD in this case. It's quite obvious you can't smooth a cube visually ?
[ and on side note, chamfer everything everywhere, for the rest of your life ]]
3:Now you apply single smooth group if there wasn't.
4:You can directly unwrap, or apply box mapping for easier proportions, and then unwrap so it wraps continually around the chamfered corners.
[ to make this step take literally few seconds, unwrap by the spline the chamfered wall now follows horizontally ]
5:Now you can safely displace the walls for visully the best result.
There are possible workaround and dirty ways:
Invert the disp map and use negative displacement: Your geo will displace against each other. No black open edges.