Review complete. I've made a few comments on the Cython python-cpp-challenge PR, as well as on some commits for the tech report (since I couldn't find a better way to make line comments on that).
There are some minor grammatical issues, but I don't think it's worth either of our time for me to go through and point them all out to you, and they don't get in the way of understanding the document at all. If you don't mind, I'll just edit the tech report source myself to make those changes?
The big comment I have is that I'd like to actually have some more "typical" wrapper code in the tech report at some level, with some annotation and a copy of the C++ code that it wraps - or at least enough that a reader can see what the Cython bindings for a typical method looks like.