I finally got tired of the super bright screen on my Moto Q straining my eyes everytime I play a late-night game of Sudoku in the dark (doesn't everbody?). Inspired by TornadoLight that I used to run on my SP5m, and by some requests on the Qusers.com forum, I decided to give this a quick go last night.
Run it the first time to set your screen to the DIM level, run it again and select YES to quit and restore the normal backlight.
Let me know how it works for you, or better yet, post your feedback on the Qusers.com thread linked above - it's a great forum.
*UPDATE* - I've posted a new version that removes the YES/NO UI prompt. Makes more sense to just have it toggle on/off and that will make disabling the Low backlight mode easier across a reboot - no need to run it twice now.