Content protection tools?

Hi,

Is there a recommended tool for content protection, i.e. monitors other sites to search for wholely/substantially matching content? I have tried copyscape but wasn’t too convinced. There were some results I would have expected to see, e.g. from other site I own that did not show in the results (using the free trial). I am assuming the paid version has the same accuracy; just allows more pages to be monitored.

Also how close does something have to be before it is reported as a copy?

Cheers.

John