I've done hundreds of touchdown autos at night, both with NVG's and without. The only time I've seen sparks was when we lost a skid shoe and the the skid tube snapped. That was impressive.
With regards to full downs being unnecessary I couldn't disagree more. The main problem that I have seen doing power recoveries is that people terminate too early. People trained to do that, unfortunately in the real event, will do what they have been trained to do. There is no use being trained to terminate an auto at 20 feet agl.
We had a technique on power recoveries where we would bring the throttle in prior to the flare. Once the flare is complete and collective is being brought in to cushion, the throttle is rolled off to terminate with a hovering auto. This works great, but be warned if you or the instructor are not very proficient at it don't try it as you can end up in a spectacular over torque.
The most important thing in a Jet Ranger at the end of an auto is GET IT LEVEL!!! You can drop a Jet Ranger from a frightening height and as long as she hits the ground level you can get away with no damage. Seen it and done it. Either that or my guardian angel was working overtime!
One last point. From an instructors point of view every autorotation should be treated as though the engine will fail and a power recovery is not an option. Then if it does fail you are not caught by surprise and are already mentally prepared to take it to the ground. Be careful where you roll that throttle off.