On a fresh install of Ubuntu 12.10, I have NOT been able to install padre or Devel::ptkdb successfully from CPAN. But if I use Ubuntu's apt-get both install and work without any problems. Since "mucking" about with the system perl is considered "not the thing to do", I want to create a user perl that takes advantage of the successfully installed modules of the system perl.
Moritz brings up an excellent point and I would be careful to configure the local perl with the options of the system perl.
As I understand it, modules installed from CPAN via the local perl would not pollute the libraries of the system perl.