I guess it depends on whether or not you care about the warnings (it seems that you don't), but more importantly whether or not the rest of your code cares.

If you're confident that it's not going to cause any unwanted side-effect, then you could probably leave them off - or better - just disable warnings for those parts of the code that are throwing them.

Personally, I always like to produce warning-free code. Sometimes, it's just a matter of doing something like next FOO if ! defined $bar;. To me, the effort involved in that is not much more than turning warnings off/on.

Cheers,
Darren :)