Here is rather convincing anecdotal evidence of the value of a PLB:
Teens Participating in Outdoor Leadership School Suffer Bear Attack near Chulitna | Vertical - Helicopter News
It is often said that ELT's fail to operate in a significant per centage (I have heard as high as 85%) of accidents. PLB's are now routinely available for about $250 street price - would seem a worthwhile bit of safety equipment. Of course, assumes that someone on board survives in a condition to operate the PLB.