OP, if you want DCC don’t let anybody talk you out of it. Sure, it might transpire to be not as bad as you first thought if you get a car without it, but it will never be as good as you originally wanted, which is what matters.
The GTI isn’t a sports car, it’s an all purpose hatch that performs all things for all men. For me DCC was an absolute must, no question, no compromise, because it's used for a multitude of things such as ferrying kids around, long motorway journeys, going out for. blast etc.
My car is used on the pot hole ridden roads of London and Surrey and I can tell you without question that ‘comfort’ mode is worth it’s weight in gold, especially recently after the floods/rain which have torn up the roads. It also makes motorway cruising so comfortable!
Horses for course, but if you are in a situation where you think you'll need some suppleness for comfort, then get it, don't hesitate. Cars with DCC also command better/stronger premiums on the used market because people now realise what it actually gives you.
As for your original question, sadly it’s a minefield, Jim sums it up nicely with his AT search hints. As for DWA cars it should be listed at the bottom of the standard features list under the “Fitted optional extras” section... however that relies on the dealer entering the details manually and correctly.
There’s no comfort connection between people fitting DCC because they have specced 19’s, the connection is normally £ related I.e Cars with 18” are more often than not basic cars.