Parameter Passing failing for tds version <> 4.3

I have been using freetds and DBD-Sybase as the cornerstone of my app since
many years ago. There is a bug in freetds or maybe something by design that
should be changed, that makes parameter-passing for stored procedures fail
using any "tds version" different than 4.2. I consulted Mike Peppler, the
author or DBD-Sybase, and presented him with a definitive proof of the
issue, and also I submitted a DBI-trace with both cases, when it works and
when it does not. He answered this "Please raise this with the FreeTDS group
- there's not much I can do, because the trace doesn't even show that the
data comes back to the application. Sorry."
 If somebody could investigate the issue, I have a Linux box ready with the
Perl script, which I copy below:
------------------
use strict;
use DBI;

my $dbh = DBI->connect("dbi:Sybase:development:1433", 'user', 'pwd',
{PrintError => 0});
die "Unable for connect to server $DBI::errstr"
    unless $dbh;
$dbh->do("use $db");
my $query = "declare \@param1 varchar(15), \@param2 money exec test_sql
\@param1 OUTPUT, \@param2 OUTPUT";
my $sth = $dbh->prepare($query);
DBI->trace(5);
          $sth->execute();

do {
      while(my $dat = $sth->fetch) {
print "TYPE $sth->{syb_result_type}\n";
print "Data @$dat[0] , @$dat[1] , @$dat[2] \n";
         if($sth->{syb_result_type} == 4042) { # it's a PARAM result
           print "Number:  $dat->[0]  \n";
            print "Varpar:  $dat->[1]  \n";
         }
      }
   } while($sth->{syb_more_results});


$sth=undef;
$dbh->disconnect; 
-----------
The stored procedure is also very simple:

create procedure test_sql
@param1 varchar(15)=null out,
@param2 money =0 out
as
set nocount on
select @param1='Freetds', @param2 =56.60
Return

The issue is that this works flawlessly only with "tds version=4.2" and it
fails with any other version, like 8.0, which I use for SQL Server 2008. Is
it Freetds, DBI or DBD-Sybase?

Thanks
Federico