Gentlemen, some v. good news. I am to take delivery of my Def4s later this month, they are currently in the hands of a reviewer which will hopefully lead to a positive professional review.
I'm actually suprised there have been no other formal reviews, bar comments of the sound at various shows.
Re the Dominance; I live in a converted loft, listening space 22' x 27' x 13', spkrs 10' apart, 12' from listening position, free space behind, close on 8000 cubic feet listening volume. The acoustic is v. live and can support bass pretty far down (esp. with the help of SpatialComputer Black Hole bass node correction). In other words, my room could certainly support these uber spkrs.
I do believe that their aluminium standard finish is too much for any enviroment, but speciality finish in black anodised to incl. driver rings and base would allow them to fit in much more easily.
There are plenty of high end spkrs as, or more, imposing eg Magico Q7, Rockport Arrakis, Wilson Alexandria, Kharma Grand Exquisite, Evolution Acoustics MM3 and 7.
For obvious reasons $50000 is a bit of a stretch, heightened by the fact that, unlike the Def4s, there is no onboard sub amp, so the cost of this plus bass filter management would have to be found.
So, a lottery win day one purchase, and an interesting parallel dimension alternative to the Def4s, but I think I'm going to be PRETTY content when my new babies arrive in a few weeks!