IMHO the far more important metrics here are whether you're testing everything, as in code coverage and so on.

Yes, you seem to understand what I'm trying to do: I want to test everything adequately (and part of that is code coverage). Portability is a very important concern. In fact, my main reservation about using $^X, system, Capture::Tiny, etc, (which is very similar to what I used to do for in-house releases for known platforms) is a concern, potentially unfounded, that I might artificially limit the platforms my distribution will install on. On the one hand, maybe I am worried for nothing, but on the other hand, I'd hate for my entire module installation to fail because a test for the script did not succeed, when the library itself would have tested and installed just fine.

Thanks for the link to your distributions that use a similar approach. Those CPAN testers matrices give me hope that I might be worried for no good reason.

I know there is more I could do, but a lesser desire is that I keep my finite efforts focused on the library itself, with proportionately less time spent on some 40-line script I am including as a useful afterthought. But, hey, that's software sometimes, I suppose.