Wing-overs are easy to fly. The danger is during the recovery.
The manoeuvre is generally taught at 300 ft agl. The height gained during the pull up could be 200 ft depending on pitch up angle.
The danger occurs during the recovery as the helicopter is accelerating downwards at the same rate as it was decelerated upwards. If the pilot does not level out at the entry height, ie 300 ft, but attempts to go much lower, he then has a much greater acceleration towards the ground, both vertically and horizontally. If he then attempts to recover with too much aft cyclic, he effectively “stalls” a large proportion of the rotor disc and the helicopter continues to descend. If he now pulls collective he increases the amount of “stall” and hits the ground! The only recovery is to reduce the aft cyclic input (difficult when you are approaching the ground fast).
This is a gotcha for even experienced pilots.