1. CPAN modules that will not work with Perl 6/Parrot.

While this is not likely to be true at launch, within a year or so Parrot should be happy to load Perl5 code therefore making the majority (if not the entirety, depending on how XS dependant modules are handled) of CPAN available to Perl6.

2. It seems that everyone is writing their very own VM these days (ex: java, .net, mono, parrot), which will (of course) run faster, better, etc than everyone elses. There is hardly a practical technical incentive (platform dependency excluded) to choose one VM over the other. Parrot will be just one in the crowd.

For the reasoning behind Parrot as YAVMI¹ see Elian's (Perl|python|Ruby) on (.NET|JVM), (closures) The reason for Parrot, part 2 and Why not a Lisp (or Scheme) VM for Parrot?.

4. Will not appeal to perl programmers because it will probably be bigger, require more typing, run slower than perl 5.

Slower than perl5? To quote the man himself - Parrot is an order of magnitude faster than perl 5 doing equivalent things. Without enabling any extraordinary measures. (see. Now I know how the Lisp folks feel).

5. They are not really thinking about making extending/embedding easier than XS.

Parrot won't use XS, so this is a non-issue.
HTH

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broquaint

¹ Yet Another Virtual Machine Implementation