Another good show Jon.
One thing about the Kindle DX that you missed is that it can display full size pdf documents without resizing them, or reflowing.  It works great for technical pdfs, like scientific papers with embed graphics and graphs for example.
It can handle very large pdf documents but changing pages is very slowwww.  

Also, it can display other formats as well, plain ASCII text for example.
On mine, there is an experimental features menu item that claims it can  retrieve web pages (via cellular I think) I have never used this feature so I don't know if or how well it works.

The DX appears to have been an attempt at a professional version of the Kindle and appears to have features that were not on other kindles, which explains its price and short life.