You have a point. But standard wisdom seems to be that you'd be even better off installing a separate copy of Perl (probably from source) and using CPAN to customize that rather than messing with the system's Perl (and this is true for any system with package management that ships with a version of Perl, not just Ubuntu). Though, getting by with the system's Perl can certainly be a simple solution that will likely work well enough for a while. Usually, you will eventually get to a point where using the system's Perl introduces conflicts, but it may take a while for that to happen for some people.

I'm not the OP but I have a related question.
I messed up my module installation(that I think I can fix) and am now looking for smarter ways to handle my Linux Perl installation. I've seen instructions for installing multiple versions of Perl, but how does that affect my ability to use CPAN or CPANPLUS?
One document for manual module installation indicated to edit Makefile.PL with the non-standard path where I would store modules. Doing that for each manually installed module would be a pain. How would CPAN/CPANPLUS handle this?
Overall what I want to do is leave the system Perl installation alone, install another version somewhere on the filesystem(probably in /opt/perl.ver ) and from that point on install as much as possible (modules)in my home directory.

Which perl executable you use to run CPAN.pm controls where modules will be installed by default. Configure your from-source version of Perl to place modules in a directory structure different from where the system Perl places them. Done.

- tye