Definitely stay with Perl5 or you may find yourself having to wait until the last day of your 24 months before you can start working on your program. Not even eXtreme Programming will save you then!
Of course there a number of Perl6 concepts already implemented as modules in Perl5: search for Perl6 on CPAN.
CountZero
"If you have four groups working on a compiler, you'll get a 4-pass compiler." - Conway's Law