I see your point, on the aircraft that started in the pits, that would wake you up a bit.
Understand though that there's a good chance he wasn't abiding by the common sense safety rules of electric power. With the battery connected, you are depending on a $.30 electronic component in a switch or speed control to keep that 18 to 24 inch prop from tearing something up.

As for the heli incident, that can happen with any kind of power plant. I sounds like some sort of connection problem, maybe battery pack to ESC, who knows, but its a big problem when any motor quits in a helicoptor.

Your concerns are valid. Everyone needs to stay alert in the pits, no matter what power systems the folks are running.

Ken

Just a side note, when anybody is playing around with their transmitter, especially with a connected electric powered plane, maybe that individual should be straddling their fuse with the stab against their legs, I don't know, it's just a thought.

Ken