My reply is a bit off topic, as it's more about testing than coding...

Anyway, especially when dealing with important clients with specific requirements (e.g. Perl can't be upgraded), you must have very good and compelling reasons NOT to develop and test under the same conditions.

Infact the difference in @ behaviour might be just one of the subtle differences, and you might realize this when you don't have time to do something about it.

Besides, my Perl 5.6.1 (GNU/Linux glibc 2.1) interpolates even if the array is undefined and does not print a literal @ unless I quote it.

If you have good reasons to keep on using a newer Perl (what about modules by the way? differences in versions can affect your development and testing even more!), it's a good idea to check the relevant perldelta manpages, just in case.

-- TMTOWTDI