Does the idle correspond with what the tac displays (I.E. does the idle hold steady on the tac or jump around with the feeling?)? Have you checked the mounts recently? When was the last time the DSG was serviced?
Check the mounts(under battery tray and pendulum((Dogbone)))? Check DSG fluid.
My '07 GTI has a slight vibration, but the tac is steady, so I just consider it part of the cars character, that slight vibration is subjective however, and I can see how it can feel like a rough idle.