I placed my order for the exact same car (3-door GTD) in white - I then spent several months being restless about it and eventually changed to Carbon Grey about a week before it went Build week confirmed! Definately the right decision I think :-)
I'm just worried about swirls, scratches and stone chips.
I had a Deep Black Pearl Mk6 and by the end of its 3 years the front looked like it had been pebble dashed. There were literally thousands of stone chips. Although I am quite anal about washing the car with the 2 bucket method, the car wasn't the best in the bright sunshine.
I've currently got an A1 in pure white metallic and while it doesn't shine up as well as a dark colour, it hides a multitude of sins.
So one day I've convinced myself its white for definite then I look at the likes of the Carbon Grey here and change my mind.
Its driving me nuts.