Dan - I admire your tenacity - but rest assured, if all else fails (and it will - you must have SOME backlash in the system otherwise it would seize up) Mach copes with backlash compensation admirably. I recently changed my lathe to ball screws, and was pleased with the results, but I still use the Mach backlash compensation.
If you think about your manual work, you always automatically compensated for backlash by always coming up to a cut in the same direction. CNC does not do this, it cuts in any direction, hence the need for backlash compensation. I must admit I still, if writing my own GCode, tend to run past the job on the return, and still always approach the cut from the same direction. I have no problems and my work is accurate and repeatable.