I haven't had any problems with Onyx, though I have only used it once. I did use Cocktail this week after seeing it recome=mended in an article and it turned out to be a disaster. After running the suite of scripts I lost my hard drive at the next restart. I managed to boot in 9 from an external drive and eventually managed to find the internal drive. I ended up having to copy, not backup, everything dear to me. Then I had to erase and reinstall on the internal drive. Lesson learned, stick with Tinker Tool and MacJanitor.