I'm not sure it's right to generalize about backlash on all rotary tables. It will be like most things CNC or milling machine related - I.e you get what you pay for.

With that said, it probably isn't worth investing in a quality rotary table for this purpose and I'm sure there probably are issues with the gear reductions on cheap rotary tables. I was thinking that, as part of the diy process, I would bypass the cheap gear reduction and use my own belt / pulley reduction (and maybe a little backlash compensation in the software).

I have also looked at used harmonic drives but I don't know enough about them yet. I have more reading to do before I understand how to shop for a decent one and how to convert one into a finished rotary axis.

Does anybody ever use a direct drive rotary axis with a larger motor to avoid backlash issues?