The !$& shortcut will fail to match zero. (I also note that the SUCCEED expression is redundant with just returning nothing.) 
my @regexen = do {
  use re 'eval';
  qr/(?:$QUOTED|$NUM)(??{FAIL if $& eq '.' or $& eq ''})/,
  qr/(?:$QUOTED|$NUM)(??{!$& || '.' eq $& ? FAIL : SUCCEED})/
};

my $teststr = 'xx0y-0z0.a..0b-0.c-.0d.d.0.0e-0.0';
print Dumper [ $teststr =~ /$_/g ] for @regexen;
__END__
$VAR1 = [
          '0',
          '-0',
          '0.',
          '.0',
          '-0.',
          '-.0',
          '.0',
          '.0e-0',
          '.0'
        ];
$VAR1 = [
          '-0',
          '0.',
          '.0',
          '-0.',
          '-.0',
          '.0',
          '.0e-0',
          '.0'
        ];

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Caution: Contents may have been coded under pressure.

In reply to Re^2: Forcing a regex to fail by Roy Johnson
in thread Forcing a regex to fail by Ovid

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