I sold my Kindle DX after getting the iPad and read all of my books on it. I don't do any reading while in direct sunlight, so that was not an issue for me. I loved the Kindle, my wife is on her third one and she won't give it up without a significant fight. Amazon makes a great device.
There are two reasons Kindle Magazine and Newspaper subscriptions aren't available on non-Kindle devices.
- Technical issues like doing Push of content to the iPad. This is being worked on.
- Apple (you guessed this right?) wants a piece of every subscription on the iPad. This is the same reason that other Magazines have not yet created Apps with paid subscriptions.
The New York Times has gotten around the issue by providing a free App with free subscriptions. They are getting the revenue through ads for now.