My understanding is that they have installed new DSP modules to Denafrips dacs. They would like you to install these on older models to get the most out of the new firmware upgrades, but aren't shouting it from the rooftops.
If I had pulled the trigger on one I would be miffed with their better/best/improved constant tweaking of all their dacs, which imo devalues what you decide to take a punt on today.
The 12th Anniversary models also have better spec than former versions.