This is just my opinion, but for me Perl 6 seems to indicate that it's just a new version of Perl, while Perl6 suggests that it's a new language. (I might just be imagining this, see TeX78 is very different from TeX, but C99 is clearly only a new version of the C standard.)

Also I recommend that you don't give too much importance to this issue. If, as you say, chromatic has said "nit", you don't have any reason to think it's a very important distinction.

Updates: Also, the Perl 6 grammar will be more sensitive to whitespace as Perl 5 is, it's not that strange that people care moer about the whitespace in the language name. :)