The aircraft I fly in occasionally for work has a 406 MHz ELT but that does not stop me from backing it up with a PLB. If we ditch and the plane sinks (after I get out), my PLB becomes primary. On a boat that can easily sail out from under SPOT coverage, why would anyone bother with a SPOT? Rhetorical question...

I have a feeling the Captain of the boat had the SPOT primarily for race tracking purposes, only secondarily for emergencies.
_________________________
Better is the Enemy of Good Enough.
Okay, what’s your point??