I'm sorry but I find the GTI to be the same ride in all settings. It can get quite crashy over poor road surfaces regardless of what setting the DCC is in. It's a reasonable ride but it will never be a great ride which is fine and expected.
Out of interest Mr Savage, where abouts are you in the country?
I would love you to have a drive in my car and see what you think of the DCC in mine as I honestly can tell a significant difference. Sure, it isn't as marked a difference as it was in my old Passat CC (that car was unbearable in Sport), but there is a clear difference and every passenger I've had in the car has commented on it.
I'm certainly not kidding myself, if I didn't think it was worthwhile I'd be more than happy to be honest and say.
The area where I live has some pretty terribly surfaced B-Roads and in Sport mode the drive is unpleasant, but in Comfort the edge is smoothed off and progress is much more fluid.
As I mention, I'd be delighted for you to drive my car if you're near to me in Lancashire to see if it is a problem with your car or a thing in general.