"One function of elevator cables is the emergency brake system "

With this maglev system (as with conventional elevators, trains and trolleys), there is a speed governor system. When the governor spins too fast, the centrifugal force activates a braking system.

It could still have the type of safety brake that mounts under the car and engages when excessive downward motion is detected.

Maybe they are based on electropermanent magnets - ie. defaults to on, current switches off.

I'm not sure how the elevator works, but if you've ever tried to toss a magnet down a copper tube, it appears to defy gravity - no electricity involved. Something similar could work to create a "fail-proof" elevator.

In this case the eletric current creates the magentism though. Turn off power and poof, gravity is back

Only half of the setup are electro magnets. The other half are permanent. If the elevator falls the permanent magnets will induce the coils.

I'm guessing there is a mechanical failsafe in place, but I want to see test data proving it works before I get in one of these

They have emergency batteries, and a mechanical brake if those fail, just like regular elevators.

Please not. I wouldn't want to put my life in the hand of a (hopefully charged) battery. Any failsafe in an elevator must be mechanical and work with total loss of power. Anything else would fail at some point. This happens with other product at some points. But elevators are one of the few products trusted by nearly everyone because they never kill anyone.

"and a mechanical brake"

This is what you want, they built in into their product.