But part of the reason Python 3 wasn't "very ambitious" is that the people building it actually accounted for what could be done, and made a distinction between "what would be nice" and "what we actually need". It's been a careful, controlled upgrade process that actually works in the real world. It really is everything that Perl 6 hasn't been.
In my considered opinion, the way that Perl 5 is partially evolving into Perl 6 even before Perl 6 is out is further evidence that a big bang was neither necessary nor desirable. There would be at least one discontinuity point, just like there is for Python 3, but that's manageable.
I'm sure Perl 6 will eventually be released, which is not something I'd say about most projects in this state, but I don't think the perl community is doing itself any favors if it fools itself into thinking this went well. It didn't. Perl 6's process has been a disaster. This point needs to be made.
I'm a professional perl programmer and don't want to see the language die, and it's been frustrating watching Perl 6 try so hard to kill it. As an open source project, they have every right to take as long as they like, I'm not trying to infringe any freedoms, but I have every right to say what I see, and what I see is not flattering at all.