When changing from one O/S version to the next I always do an erase and install. Once back in the early days of OS X I did an archive and install and had a few issues, so I did a clean install and it was fine. It just seems logical to me.
I sure wish the clean install would of helped me. When I bought Leopard, i did a clean install, only backing up my music,bookmarks, and address book. And I am having still having Kernel Panics 5-6 times a day.