If it's backwards compatible, and if speed is the utility function, yes. Surprisingly, unless I'm missing something, it's even faster than refaddr, at least for my environment (perl 5.8.6 on linux i386).

Update: clearly, what I'm missing is reading the docs to Benchmark and proofreading my code. Stupid errors fixed, I hope. 0 + $ref still seems to be faster than the XS refaddr, which is surprising, but maybe that's the function call overhead.

use strict;
use warnings;
use Scalar::Util qw( refaddr );
use Benchmark qw( cmpthese );

my $ref = {};

cmpthese( -5, {
    'xs   ' => sub { refaddr $ref },
    'regex' => sub { "$ref" =~ /0x(\w+)/; hex $1; },
    '0+ref' => sub { 0 + $ref },
});
[download]

Result:

           Rate regex xs    0+ref
regex  165816/s    --  -89%  -97%
xs    1504549/s  807%    --  -73%
0+ref 5550057/s 3247%  269%    --
[download]