Relying on undocumented behaviour is not only dangerous for compiling in future versions (like Hauke pointed out), you'll also sabotage many external tools trying to parse your code.

For instance, I once had to edit code where =h1 (and so on) was used instead of =head1 , guess how well the syntax highlighting reacted with an not so forgiving editor?

And last but not least many (all?) podparser should fail, do you really want to rule out any documentation?