Rosalind - 9:20 pm on Aug 5, 2012 (gmt 0)
I've been doing a merge and purge on a much smaller site this week. My approach has always been to have a more comprehensive internal search than Google's engine. So the information is still there, but in some cases it's part of the deep web unless someone else links to it.
However if the engines don't like it, and people aren't sharing it, it's important to be ruthless.