I just quickly covered the black version of the Go7 with white tape for comparison with the "white" version and the effect on the contrast was negligible.
PS: I applied the tape a bit hastily, especially around the buttons, so it looks a bit sloppy
I was surprised by the very good contrast and sharpness of the text when I compared the “black Go 7” and the latest version of the “Kindle WhitePaper” (with the same E-INK 1300 screen) side by side, the black version of the Go 7 has slightly better contrast, both in text and when browsing manga, for example.