You bring up a serious point about EDF. High powers/RPM & no protection.
I tie my planes down with 1/4 Nylon line to test them. I KNOW if it blew out, I would let go anyway.
Not to smart in a basement or garage ??
I have only overrevved 1 Fan delibertly. GWS 40 mm. Went so high the noise became 1/2 as loud NEAR WOT. 2 Hyperions 5800 KV running on a charged up car battery. Hard to tell if I became afraid as it ran quiter at higher revs.
My hearing is tested as good.