Using external programs makes you very dependable of it's parameters and features. In Perl modules updates, mostly compatibility with older versions is taken care of. For security you should choose the module i think, spawning means extra risc for bugs in another program.

I think you have more control of security with a module then of an external program started with parameters.

Q: Why did the Perlmonk cross the road?
A: He wanted to escape the match.