Automation heavy is a good thing in my book. I think whether the developer writes it is often a function of what you're testing.  For example, WinRunner has its own learning curve, and so seems to be left to QA more often.  Whereas Selenium seems to have a smaller curve.<p>Generally though, I like the idea of someone else proofreading my work, because for the same reason that I forgot to account for a set of inputs, I will tend to forget to test with those inputs.