I do vaguely recall of serious-injury accidents where the wreckage was found sooner due to an ELT but (from memory) it was more due to the 121.50 emission than the 406MHz satellite-location signal.
I've never heard of the 406MHz signal making a difference to saving a life, but then I haven't read every accident report
I would strongly expect 406 to make a difference in ditching / life raft cases, but they seem rare in Europe anyway. Very rare indeed for the pilot to be out of VHF contact, and any such contact, never mind setting 7700, is likely to make the 406 part redundant.
The general view in the USA seems to be that 406 is nearly useless because most people (who might survive at all) manage to get a radio call out, and that narrows the search area to the extent that again the 121.5 emission (only) matters. This is a factor behind the significant back-pedalling in the USA and Canada on making 406 mandatory.
In Europe, legislation doesn't often get based on evidence
