I would disagree with this. I feel that saying "use 5.006;" when you haven't tested with older Perls means "I am only willing to support 5.006 or higher". I had a big internal debate about this with
and decided that I simply didn't have the time to worry about 5.005_03 and the like. So, I put it in and that freed me up to use features that are 5.006+ with impunity (such as 3-arg open, warnings, our, and the like). This was a deliberate choice that was based on non-code-related factors.