Okay I went and took another look and took some better photos. You can see all the photos here: http://www.positivebias.com/ebooks/
including some taken directly next to the prs700. After seeing them side by side again, I would say that the 600 is better than the 700, marginally. The 300 and 505 are definitely crisper though, and handle glare much better, as you can see in the first 2 photos in the gallery.
I'm also uploading a much longer video which shows the 505, 300 and 600 side by side with a good example of the different colors of the readers as well as how they handle glare.
I was even considering the 300 until I saw that it is plastic all the way along the edge as opposed to shiny metal like all the others. I guess they have to hit a price point somehow, right?
The movie can be found here: http://www.positivebias.com/ebooks/ebookreaders.mov
at about 1:30 MST (Central)... sorry, it's still uploading.
I'll field any question I can answer, if people have them.