Great idea! I love watching the results pop up as I make or change choices.
Love my eReaders: I have a Sony PRS-900 (Daily Edition, but not as nice as the 950 with its pearl e-ink) and an Entourage Pocket Edge (which is an interesting device I'm still exploring).
I agree with The_Terminator that Kobo needs to be on your list, and I think it might be important to distinguish between iterations of Sonys. Also, I would love to see the Entourage Edges in your comparison! They have 2 screens, one e-ink (Vizplex) and one LCD (Linux/Android), which work together for a pretty amazing reading experience.
Keep up the good work!