Okay, after posting the question above, I asked myself "Self, what about using a regex instead of some new-fangled module?"

So I came up with the following:

#!/usr/bin/perl -w
use strict;

my $oldfile    ='./existing.xml';
my $updatefile    ='./update.xml';
my $newfile    ='./new.xml';
my ($old,$update);

{
# read in the two files
local $/;
open OLD, $oldfile or die "$!";
$old=<OLD>;
close OLD;
open UP, $updatefile or die "$!";
$update=<UP>;
close UP;
}

$update =~ s/^.*(\<dbf>.*\<\/dbf>).*$/$1/sgi;
my $up=$1;

$old =~ s/\<dbf>.*\<\/dbf>/$up/sgi;

open NEW, ">$newfile" or die "$!";
print NEW "$old";
close NEW;
exit();
[download]

Which seems to work fine for what I'm doing (replacing everything between nodes).

Let me know if I did anything stupid here. Otherwise thanks for thinking good thoughts.

db