That is precisely what the 400 does. Bill has managed not to make an entirely different sounding deck but to build on his previous strengths. High mass decks usually differ considerably from the lighter options but the 400 builds on the sence of air and flow whilst adding considerable authority. John Bonham and JPJ have never sounded so 'heavy', as when I had the 400 home, not even with my Naim 500 system and a tricked up LP12. By comparison the Versalex sounds a tad soft and slow, I kid you not. A straight a+b and I'm gutted tbh. The perils of working with this stuff. Nothing I can do gets the Versalex anywhere near the 400 and I have tried. Removing feet, using Still Points, myrtle wood blocks, Sorbothene spheres and various bases, all change the sound to some degree but none add that bottom end the 400 does so effortlessly. Once heard never forgotten. Bugger.
I agree totally with your last point, my experience precisely.