I have been in the same situation, trying to decide between several readers- mostly BeBook, Sony 505, Sony 700 or even the Kindle. I also have many technical/scientific PDF documents to read, probably many public domain classic books and, if the price is right, some purchased books.
I read about the screen issue of the 700 vs. the 505 and decided to see for myself. I copied a few files onto an SD card and plugged them into both Sony Readers and the local Borders shop.
Yes, the contrast on the 700 screen is less than the 505 and text seemed crisper on the 505. But, the 505 was sluggish when opening PDF files. Sluggish, at least in comparison with the 700. The zoom provided another way to look at PDF's, but it was a bit cumbersome. Changing the text size worked better on some files than others - I need to learn more about converting PDF files...
So, considering PDF's, I'm leaning towards the 700. The screen is readible, just not as bright. There was a recent post of someone trying to remove the LED lights and eliminating a gap in the screen construction to improve clarity - not sure of the progress.
For the BeBook- I like to ability to read in different fonts. However, I've read that fonts can be embedded into ePub files - but I don't know anything more than that. Not sure how it's done and if fonts for foreign languages can be embedded?
Good luck deciding, I'm still researching and learning.
