While stumbling the web, I came across Senocular's ActionScript 3.0 Tip of the Day thread on Kirupa.com's forum.  While the the original thread might be old, its content is rich and very informative to those looking for good reasons to stick with ActionScript 3.0.  Topics include: event handling, stage access, MXMLC meta-data tags, XML and E4X, Flash 9 , and many more.  Enjoy!