Yeah, the only problem is that M10 and M11 are for turning a pallet or axis clamp on and off on Fanucs. Sometimes they are used to turn vacuum on a table on and off. So I really don't want to use those. And I really don't want to use M codes at all because M codes currently break the CV chain and we would have to add an exception. But we may have to. I would rather join up with LinuxCNC and try to create a standard than try to create something from scratch or use some code that already has uses.
Mach 4 mill (and lathe is almost done) is what we currently have. Lathe is a whole separate interpreter! We plan on having a separate G code interpreters for laser, plasma, water jets, and tangential knifes. These will come at at later date. One interpreter doesn't have to do it all in Mach 4. Until then, try the sleep trick and see if you can get it better. I'm pretty amazed at what you are doing with the laser and the mill interpreter!
Steve