I would only suggest caution in the interpretation of any studies. There are studies which suggest some people prefer reading on an iPad to a Kindle. The point is that there is huge individual variation in terms of which screen is preferred. I have had an eInk device for about 5 years, and I think they are great for reading. I also read alot on my iPad, and find reading books on the iPad to be painless and a great experience. But, as above, some people find reading on a LCD screen to be painful. There is no one best solution for everyone.