They seemed less reliable than LEDs. When they were common here they would always have tens of dots stuck in the wrong position.
The old panels had diode issues. It wasn’t the mechanism failing — the simplicity of electromagnets means they last an insanely long time, significantly longer than an LED. The diodes were just cheap and undersized. If you have a stuck disc on an old board, 99% chance you just need to replace the diode. If it still flips but gets stuck on one side, a pin has gotten sticky and needs graphite applied.