Got bungs on the Thou, no intention of testing them
Had engine bars on my old CB900 years ago, saved the engine when I had an off, but I think it contributed to the damage to the rest of the bike. But then the engine is more expensive to replace/repair than most of the rest, so I guess it's down to your preference.
But as Graham said there has been instances where they've contributed to upper leg injuries, if I'd not come off before it hit the deck, my leg would have been under it, instead the bars,tank and seat took it