You may want to consider returning the Kindle DX if your use case is PDF reading, particularly if you have any complex graphics, and absolutely if random flipping through the document occurs.

I own a K1 and K2 - and nothing beats them, not even paper, for bright sunlight reading. I had a DX for about a week, but found that the page flipping performance in textbook class PDFs, particularly when I was looking for a random page was poor, and, the Achilles's heel - complex graphics took several seconds to render.

The iPad is a better tool for that use case, and, with dropbox + goodreader, it takes me all of 5 seconds to bounce my PDF onto my iPad for future reading (With the bonus that my iPhone now has access to the same PDFs, and, I have full access to color documents.)

I do 100% of my summer reading outside on my Kindle, though - wouldn't even attempt it on an iPad, even with the matte screen that I've added.