I have 17s on mine, and I actually prefer them. They are more subtle - give the car a bit more of a classy look. 18s are just a bit too showy. But that all depends on what you like to be honest! But I certainly wouldnt say it didnt do it justice... perhaps its very colour dependent
The GTD is like a blow up doll. The GTI is like a proper woman. Sure the doll might last longer, and the woman might have higher running costs, but which would you rather have?