Decided on the Sony 700
I've been lurking these forums and heard--and saw!--about the screen/display issues (700 not as clear or crisp as previous model 505), and finally got down to the nearest Sony Style store to handle the two models myself. I had already decided on a Sony because of their support of secure PDF documents, of which I have a (growing) number that I do not want to convert or alter to make them work on an e-book reader.
I'm sold! I had an SD card with a variety of documents typical of what I want to be able to read on an e-book reader, and the 505 couldn't read the card, while the 700 handled it without any trouble, seamlessly inserting the files from the card into the index of available, readable files.
As for the screens, yes, the 505 was more crisp. However I had no trouble at all using the 700, and when I had used both for a while--switching back and forth--I noticed that I kept on touching the 505 screen in attempts to interact with it! I had gotten hooked on the touch screen functionality of the 700 without realizing it, and kept trying to use 'touch screen' features on the 505, which of course doesn't have them!
So there you go; everyone has their own reasons and needs for what they want from their e-book reader, and for me the 700's additional functionality was much more important than the inferior screen display.
Of course all that said, I am going to wait until next spring--just because it will be that long to save up the disposable cash to buy the 700--and if any new, big, flex screen e-book reader can match the PDF support (and speed of PDF display) and let me get my hands on them to test them, I might change my mind again.