In general they help in event of a lay down on a flat surface. But anything can happen if it is not flat ground.
When I bought my FZ, it had Rimoza sliders. Nice billet aluminum and fit well, but they didn't protrude a lot. Never. Laid it down but my worry was if I did, the radiator would get damaged.
Found a deal on the Yamaha OEM sliders. The week I out them on I had an abrupt stop parking accident in which I was off balance, steering was off center and my leg buckled. The new longer OEM sliders did a good job. My shift lever bent slightly and bar end got a scuff.