I agree with most of what you say, but I think you are overestimating the "version diversity" of CPANTS. For example, for one of my modules that's been there for a while and has 34 test results, only one has a version < 5.8.0, and this was a lucky exception. ;-) Most of the test results are for 5.8.5 to 5.8.8. There is a bias towards bleeding edge versions among CPAN testers (I even have results from versions > 5.9.0).