Another vote for carbon grey, a stunning, classy colour which suits both the GTI and GTD alike. I just wish it had been available for the R, as I would have been seriously tempted away from DBP.
For some reason I don't think the DPB suits the GTI, it's to do with the red stripe through the headlights, doesn't look quite right. You also lose some of the aggressive front detailing against black.
I think the metallic colours (as opposed to pearlescent) make the most of the sharper lines and creases of the mk7. Never a fan of silver previously but really think it the Reflex Silver suits this GTI. Solid colours look good but agree that the red stripe gets lost on a red car.
Ultimately it's a subjective thing and you could spend an age umming and ahhing over it, and the numerous conflicting opinions on a forum only make it worse
Go with your gut feeling.