At some point older versions will not be supported and have unpatched security vulnerabilities
I don't think this is valid argument for RHEL. They maintain and fix perl by their selves AFAIK.
module updates won't run on older versions of Perl
I didn't see much modules, which won't work on perl 5.10 and even 5.8 (but I didn't check some huge frameworks)

In reply to Re^2: Why upgrade perl? by vsespb
in thread Why upgrade perl? by poulhs

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