Yea, I'm pretty good at asking questions like that... I spent close to 10 years working in Quality Assurance/Control.
As for your math, I went over it a few times my head and it appears sound. Of course, unless I had an example of each sitting on the test bench in front of me, I wouldn't be 100% sure.
The reason I asked is because thinking back, the backlash was paradoxical on the machines I worked on. The rotary axes all used a belt driven worm gear and planetary setup. Interestingly, the smaller the overall rotary, the more belt stretch and adjustments that had to be done to the belt. Conversely, the bigger and heavier the rotary axes, the more I had to play with the adjustments in the physical gear meshing. Unfortunately, I really have no idea where the forces amounts would be at the break even point (meaning equal adjustment on the gears and the belt).
Then again, I'm not even sure my observations are even germane to your machine... I just drive alot for my job and so I sit there and ponder stuff that I find interesting...