FWIW and no offense to the developers of Duality, every system and OS X install on which I've used any version of Duality..died. Meaning that I had to reformat and reinstall the OS.

It could have been any combination of apps but that commonality stands out in my mind.

The reinstall was usually needed within a few days to a week of switching the theme with Duality.
I've even used the same themes with earlier versions of duality and themechanger and have had no problems (yet ? ) with themechanger.

I don't understand why that would be but that's my experience.

YMMV