My wife had prolapsed disc from accident many years ago and the Audi seats used to set her twinges off quite readily, however the last 3 years with the GTD she has not complained once and in fact after we have been walking the return to the GTD and the heated seats is seen as a form of therapy.
Another reason we stayed with the MK 7 that forgot to mention, as she made it pretty clear in the Audi garages that the Golf was her preferred car.
Drove to Lake District recently on a near 5 hour journey and got out as fresh as could expect outside of a true luxury cruiser.
Not sure if the DCC aids this? as obviously you get no crashes or anything like that which would jar the back
But one of things which is a plus, well supported with no sideways movement, comfortable and with the heat added, even therapeutic

Think all the elements are there for the comfort, so its getting the seat set up correct for posture maybe?