Actually the thing that sold me on kindle was that you can use dropbox with it as well, trough the dropbox website interface. I can imagine that it will be a sub-par experience and probably it will not take 5 seconds but oh well. And yes, the plan was to try it out and return it in the worst case.
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.