By mentioning the other factors that Mike's speakers get right
I guess you can tell I'm an advocate of W-M/T-W designs
To me, in general these configurations are the best combination of point source like imaging and even, room energizing mid-bass (even across a wide area in terms of height, width
and depth). Generally speaking, speakers like Mike's have no problems with image stability over wide coverage areas as well as near field. As Ron mentions the driver distances are close together.
Cool thing is that there are "mini" or "smaller" concentric array speakers like those from Dynaudio, Monitor Audio, Triangle, Focus, Albedo, Endeavor, Tyler, Duntech , VSA's VR-100s and not just the really, really large like the Arrakis, VR-11s, U11s, MM3s, MM7s.
The only thing is these types are tall with lots of drivers and can dominate any room visually. Even the smaller ones. Not the best choice for a shared space for the vast majority to whom family acceptance factor matters. In a dedicated space however....yeehaw!
Overall though I think that while speakers can be made to work in spaces that may be small on the outset given smart planning, it is just easier to start with speakers in rooms they can breathe. One thing I did notice however is that there seems to be an exaggeration of just how much space is optimal. I dunno, maybe because exhibitors in shows have been putting small speakers in very large rooms 15 ft apart lately? HP's rule of thirds being applied where they shouldn't? shrug. Walls are our friends and too big a room is a harder problem to solve than too small IMO and IME. At the end of the day, it is always wise to ask the manufacturer how their speakers were intended to be placed and used. This information I believe, is very valuable.