I am not aware of any incidences in Europe where an ELT has made the difference. Mobile phones - loads of them! ELTs - none - although to be fair manfatory fitment or carriage is a new requirement.
For what it is worth Steve Fossett's aircraft had a 121.5 ELT fitted (as do virtually all N-reg aircraft). But it presumably did not survive the impact. The wrist watch thingy is advertised to have a "100 mile range", the ones we used to use offshore - 10 times bigger, were good for 5 to 10 miles..........