Ok, I got my JetBook Color 2 Black. For comparison I laid the JetBook Color 2 with a white screen to my Kindle Paperwhite (disabled sidelights).
@Nate the great, doesn't look that 'annoying greyish' to me AND the white is a lot of better than with the original JBC.
The firmware seems to be the same but the screen seems to be more brilliant and faster. I'll try some colored e-books on it but on first sight it's more fun to navigate through the pages.
Unfortunately it's also a little bi more glare - we'll see how it will be in direct sunlight.
If somebody has a good test picture (1600x1200 in JPEG format) I could do a 'real color' comparison. If wanted send me the picture or publish it.