So I haven't forgotten the project, far from it! Having worked on some new pieces recently, including my "title track" Empty Threats, I now get to edit down the contents of the book. This makes me pretty happy as I don't feel some of the older pieces are really up to the quality that I want.
The key, however, is to stick at it, actually make progress, and decide when it's finished and get it converted to pdf ready for printing.
Still a while from the finish line, but trying to keep the effort up nonetheless. Especially after a few false starts. Onward!