If you read scientific journal papers, the vast majority in PDF format, i would recommend the Kindle DX. Only a screen that size can render the text and graphs, plus images with acceptable quality in a single page. Due to the nature of the papers i read, most of the time i have to have the whole page visible, legible and with the layout as published, so reflow does not work for me, and landscape view requires too much ups and downs. Besides that, technical books look great in that screen. I no longer have paper books even to teach my courses.
I am a fan of Sony products, but i could not read journal papers in my 5 or 6 inches screen readers. The 9.7 screen has saved me a lot of printing so far, with the added bonus that i now carry with me most, if not all the papers i downloaded since a long time ago. No more piles of journal papers lying in my desk anymore! It was a very good investment.
