Come on, don't exaggerate -- dualvar has to be explicitly imported and used. (I've never seen it in the wild, I have no clue what Perl::Critic says? Edit: pbp has nothing to say about them?)
And I'm not touching the "Perl 6" naming discussion.
There is inlining for using Perl 5 libraries in Perl 6, which smoothen the road. But it is a hard start to motivate projects in a new language, which is incrementally better. I would be happy to try.
Dualvars come up naturally. Treat a number as a string (try using Data::Dumper on some scalars) and suddenly your json ends up coming out like: {"something": "12"} rather than {"something": 12}
Just because both slots are filled with the same "value" in perl, doesn't mean it's _not_ a dualvar. It's just a side-effect of the way scalars in Perl work.
And I'm not touching the "Perl 6" naming discussion.
There is inlining for using Perl 5 libraries in Perl 6, which smoothen the road. But it is a hard start to motivate projects in a new language, which is incrementally better. I would be happy to try.