Just go with your heart, and if you want white, change it to white. I might be biased, but I find white by far the best suited colour for the GTI, as it picks out all the lines and accents really well. As already mentioned too, the pano roof will kinda' get lots in darker colours.
White can go out of fashion tomorrow for all I care. I've had white cars way before they became the fashion, and I'll continue to have them. My car is there to please me, not please other people!