Of all the things you list, the only ones that matter even a little bit to me are bug fixes and documentation. Unicode was still broken last time I looked (I think variable length character encodings are broken by design), any multi-threading I need can be faked up with select() and be more portable that way, I rarely use signals, and 5.005 was fast enough.

What matters to me most is, like you, that I can be confident in using new releases from the CPAN. Second comes use warnings; use diagnostics;.