Quick update on this. Our GTD went for its first service yesterday and it has come back a little quieter.
At idle, static revving and pulling away slowly in first it seems quieter. Normal driving and outside the car it doesn't seem any different.
Makes me wonder if the parameters have been changed for the internal sounder given the feedback people have been making about it. I know VW have made changes to the exhaust flaps on the R at idle/low rpm too.
Personally not too bothered, it seems less rough around the edges now, so it might yet be an improvement