While loading my fendered bike into my van with the front wheel removed, I accidentally dropped the front down onto the floor of the van. The safety tabs worked as advertised and it popped open with no damage to the fender or the tabs. (I just reattached them.) I now have them on my other fendered bike.
Picked up a large stick. safety tabs worked as advertised. However the Front just had the plastic crack at the attachment point so there's room for improvement.
I had a squirrel run into my front wheel recently while riding to work. One tab ejected, the other sheared off. The squirrel was ejected and lived. I managed to stay upright and on my bike. I'm not positive that the safety tabs saved me from an endo and more damage to my bike, but it appears that they did their job.