I just returned from vacation and my K2 has the sun fading issue. I spent most of yesterday at Busch Gardens and only found the sun fading problem when the sun was shining directly on the screen. Since I tend to stick to the shade this didn't start until later in the afternoon when the sun angle was lower. The page itself didn't fade, fading only happened when I turned the page. A quick Alt-G returned the screen to full contrast. If my head partially blocked the Kindle during a page turn only the part of the screen directly in the sun was faded. Hitting Alt-G fixed the contrast problem.
Haven't decided whether to return it since I rarely read in direct sunlight and Alt-G fixes the problem for that page.