As someone who has now heard both the Nimbus Black and the White, I can report that they both sound fabulous. Not having them side-by-side and listening to them over a month apart, I cannot give much account of the differences.
I can say that I was a bit concerned with the ceramic drivers being a bit bright and fatiguing, and was listening closely for this when I heard the White. No fatigue or brightness, but gobs of detail. A hard balance to achieve!
A review like the one mentioned above always helps. Doug did a fantastic job of contextualizing the Vapors, and his comments here and on his system page provide some nice additional detail. A fabulous speaker, well worth finding a way to listen to.