The extended research is probably an excellent idea, especially for antiquated easements. When I was in law school, I remember one of our professors telling us about Chicago's oldest easement. It dated back to some time in the early l9th century. Some farmer walked his cattle through what is now downtown Chicgo to allow them to drink from the Chicago River. In order to get a release apparently all of the farmer's descendants would need to be located and their signatures obtained on a release. No one has ever done that...so the easement remains in effect.