Never done a clean install, never needed one. They're way too disruptive. That's why I use a Mac.
Nothing beats a fresh reformat!
Could not have said it any better myself. I have been a Mac user for only 3 years now and only had to upgrade to Tiger, but I have never reformatted either of my Macs. Upgrade for me all the way!
Clean install. Since I clone my hard drive every night, I will simply use the migration assistant to put everything back in place on my new install.