use vars qw/ $re_balanced_angles /;
our $re_balanced_angles = qr{(?^:(?^:(?:\<(?:(?>[^\<\>]+)|(??{ $re_balanced_angles }))*\>)))}; 
...

        m{
### no more ## \G( $allowed )( $RE{balanced}{-parens=>'<>'} )
\G( $allowed )( $re_balanced_angles )
        }gcsx and do {