Switching from Perl5 to Perl6 isn't completely shocking, but it's not just copying code over to a new project either. Programming in Perl6 back to back with programming in Perl5 indeed feels quite a bit like switching back and forth between Perl5 and Ruby. Everything's similar enough that you have to mind the differences. It's a much different feeling than going back and forth between C and JavaScript or between Forth and Pascal where the syntaxes are so different you'd never try the other way to do something for just a couple of lines.