There seems to be not much difference between the output of the two. The advantage of re debug is that you can turn it on and off (with "no re 'debug';") inside the script to limit the output you are getting.

Here is a diff between the output of the two debug methods on your program (without warnings,data::dumper, strict, as these produce output too):

1a2
> rarest char : at 9
6a8
> rarest char x at 2
11a14,17
> Omitting $` $& $' support.
>
> EXECUTING...
>
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As you can see there are only 4 non-empty lines different between the two