[Gran Turismo]

I've ordered my B5 with original DG one week before the Fukushima thing happened, and finally got DGII as it takes about 3 months until BMW pre-builds an ordered car for Alpina for their own final assembly. See pics under "my Garage" over at bimmerfest (same nickname).

My guess is that in a side by side picture - if such a thing would exist - you probably wouldn't notice any difference. However DGII might look a tad darker under some lighting conditions, as the sparkle is less intense due to the smaller reflecting "flakes" in the paint.

No swirl marks on mine yet, strictly using car washes with textile strip brushes only (when really necessary), or just spraying the worst (bugs, dust, etc.) away weekly with pressured water in a DYI car wash bay.
If you ever go to a big car show with many different BMW's exhibited, you'll notice that the worst colors regarding swirl marks and fine scratches are clearly the dark blue ones and those with a blue hue like carbon black!