Fixed or portable, your choice, but the failure rate of fixed ELT in real accidents is better (or is that worse) than 95%.
Is that 95% all accidents, or 95% of accidents where there was a survivor that may have benefited? What is the rate of triggering of portable beacons in the same type of accidents?
To me, the ELT is most important so you can be found quickly if you have crashed and survived. I am not confident that you would always be physically able to activate a portable ELT (broken bones etc.)