Thanks for the tip. I am not sure I understand how to use it, though.
My purpose, as you have pointed out, is to replace Regexp::Common with some normal Perl RegEx. By normal I mean a non-module dependant expression.
As for the motivation, you guessed right that it's related to education. Personally, I wouldn't bother. I need to distribute this module as part of a more extensive educational material aiming at the build-up of a huge database. I would like to avoid pointing to a CPAN module, since many people in the audience are not experienced Perl users. They should just copy this module to their computers and execute the import/export script.
Of course I can provide them with a copy of the module, or instruct them to connect to the CPAN, download the module and install it, or use "perl -MCPAN -e shell" but it would steal valuable time from my lectures.

That aside, here is a test script for your RegEx, which does not seem to give me what I want.
Was it my misunderstanding, or were you trying to show me how to catch the inner parenthesized text only?

#!/usr/bin/perl -w
use strict;
use Regexp::Common;

my $re = qr{ \( (?: (?> [^()]+ ) | (??{ $re }))* \) }x;

my $input = "aa bb cc (dd ee (ff gg (hh) jj) kk)";

print "With module\n";
while ($input =~ m/(\w+|$RE{balanced}{-parens=>'()'})\s*/g) { 
    print "$1\n";
}

print "With recursive RegExp\n";
while ($input =~ m/(\w+|$re)\s*/g) { 
    print "$1\n";
}

__END__
# output: 
With module
aa
bb
cc
(dd ee (ff gg (hh) jj) kk)

With recursive RegExp
aa
bb
cc
dd
ee
ff
gg
(hh)
jj
kk
[download]

update
Found the problem. Recursive RegExes don't work properly with use strict
Changing

my $re = qr{ \( (?: (?> [^()]+ ) | (??{ $re }))* \) }x;
[download]

into

no strict 'vars';
$rec_re = qr{ \( (?: (?> [^()]+ ) | (??{ $rec_re }))* \) }x;
my $re = $rec_re;
use strict;
[download]

makes the same output from both regexes.

 _  _ _  _  
(_|| | |(_|><
 _|   

---

---

• Are you posting in the right place? Check out Where do I post X? to know for sure.
• Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:

  <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>

• Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
• Want more info? How to link or How to display code and escape characters are good places to start.