I have had 1 ½ mag failures in the air and just made it to a runway run by a parachuting club (Scotland) before I ran out of height.
The Rotax system is very good as it uses discharge capacitors, and providing the crank is rotating at 300rpm is independent of the conventional electrical system. The system is a fraction of the weight of a mag and does not have the 500h maintenance program, being totally maintenance free.
Rod1