Rakudo mostly lacks IO to be a proper superset, as well as concurrency.
Why don't you people get the spec finished before starting to implement anything ?
If you write code while not having a finished spec you're probably writing code that will get deleted on further revisions of the spec so you're basically wasting time.
So why don't the people with a good CS background in the Perl6 team just meet up and finish the spec and then you can start implementing ?
I think (although old) the waterfall methodology of developing software is the best one. Agile is really not good, except for teams of people who really have to rush to get something done(crappy, real-world software), but it is not the case with Perl6 if you say you want to write something good, there should be no hurry involved, just finish the spec already so you can get to the next phases.