My PLB is 406mhz and 121.5 as you say.
Non-PC Plod - true sometimes; depends on the impact. But then an ELT sinks with the air frame whilst you float about waiting to be rescued.
Not going to solve this one. I am not a strong believer that all machines need to carry an ELT; I would prefer the option of ELT / PLB to suit the use of the machine. I can't have that as I don't write the law, hence ELT is fitted as mandated.