The GTD's drivetrain seems to be more overengineered than that of the GTI and R. Plenty of R owners pushing out 360PS and GTI owners getting into stock R territory with a box or remap that have slipped their clutch, haven't heard of a GTD owner doing the same with mods to get them to around 240PS/500Nm.
It would be interesting to know if the 2.0TDI BiTurbo lump in the Passat has the same clutch and flywheel as the single turbo variants.