Why not use different delimiters on the whole replacement expression? I usually use curly braces when there are slashes in either side, e.g. s{some/path}{other/path}. See perlop under Quote-and-Quote-like-Operators for more details.

Also note that perl comes with a -p switch, which does the -n and print for you.

perl -ple 's{(.*) SYSTEM (.*)}{$1 SYSTEM "../../../../../Reporting/bin
+/report.dtd">}g' 1-report.xml
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