im going to speculate a little here..
Some time ago i heard story that the Claridy Amplifiers that was Develop by Ken Kreisel and Claridy itself, they started to be commercialised to other brand of subs other than the DXD12012 and DXD808, this i believe was one of the reasons the previous subs was discontinued.
If this new Subs DXD1000 & DXD500 are the replacement of previous models, they must have a different type of amplifier.
It requires time (years) to improve such good product, and im sure the new generation will sound has good has the previous generation, if not better.