Which versions of perl are available in your OS vendor's repositories is all about running the scripts that you are paying support for.
Instead of a version that is in the repositories, you probably want a home built copy of perl in some place like /usr/local/bin . This way your scripts can call it for the latest in Unicode/RegEx/Feature support and the vendor's perl scripts can run off the vendor's version.
Building Perl on Unix/Linux is easy, and since you won't be using the system's perl for custom coding, you won't need to update CPAN modules against the 5.8 lib/ directories. In fact keeping your modules up to date against a current version of perl will probably be (only slightly) less effort.