When I started the thread, my motivation was to share knowledge and to encourage others to proceed. The CPLD code worked well enough for a basic driver. I don't think there is a compelling need for improvements. My only complaint is that it produces a slight hiss when idling. That is probably caused by the lack of a ground plane.
This is not a project with widespread interest. That is why there is little interest to turn it into a production ready project or a small scale commercial product. The $10 tb6600 works well enough for most home users. Business users can easily justify buying the higher cost drivers.
I didn't go beyond building one prototype because I moved to a DSP based design to experiment with resonance damping and closed loop control. It was mainly for fun because the tb6600 worked well enough on my sx3 mill.