Excellent answer.

> If you're doing anything serious with Perl you DO NOT want to use the OS' perl as that way lies much pain

Strongly agree! Update: see also Re: Replicate Perl setup (Building and Installing Perl References)

Unfortunately in Re^4: Rediscovering Hubris (in January) the OP stated:

I also failed to communicate something that impacts what you wrote. I work on system tools that rely on the customer's OS version of Perl. We don't embed Perl into the tool, and the customer base tends to use older OS versions.