Speedw - fastest system ever?

Since I've resumed my Pitman New Era studies, my attention has been brought again to this system found on the wonderfull archive.org.

Was wondering if anybody has heard anything about it or has any opinions?

It looks super fast and simpler than Pitman, and maybe even simpler than the older versions of Gregg. It uses Gregg-like forward motion charachters, but omits the vowels for the most part and uses position writing exactly as per Pitman.

Any opinions?

Here's the textbook:

(by wordsigner for everyone)