An interesting little twist in my comparision arrived today. I ordered a used Kobo Glo on Ebay at a very low price after reading in these forums how much better it's screen is than the Aura's screen. It arrived today, several days early and, lo and behold, it's a new one in a factory sealed box. I had ordered a pink one because it was cheaper although I much prefer black, and sure enough, they sent me a black one.
Nice!
Anyway, this screen really is a lot better than the Aura's screen so I'll be continuing the comparison with it. However, it's still only fair when compared to the Voyage or even to the Paperwhite. The light is much more even now but the text just doesn't have the darkness of the Kindle text. On the Kindle, as the light brightens the background whitens and the text stays black up to about 70% and after that the text begins to grey as well. On the Kobo as the light brightens the text also lightens as the background whitens so you don't really get the contrast.
That's not terrible. The contrast is okay. It's very readable. The Kindles are just better by quite a lot.
Barry