On a side note: whatever you do for a living, please read the rest of the book. It is really good advice how to not make eyes bleed.
The thing I like most about racket is the typed racket variant because of its static type system.
Have you used Qi?
Now that is a an interesting question and thanks for reminding it! Long time ago I was quite curious about it because of the turing completeness of its own type system. I cannot recall all the reasons why it did not stick with me even if just for personal use but the licensing choices were kind of bewildering (speaking for Qi II).
For the record, the successor to Qi is Shen and Mark Tarver himself thinks that it is a better Qi. I still have to play with Shen to be honest, so I doubt if any comment of mine on Shen would do it justice.