each bag has had two more or less stationary drops - the right one being twice onto lumpy rocks. Survived with no more than a scratch on all four occasions.
Fifth time was moving at about 15mph and ditched it in a hairpin turn when it all went to a fine talcum powder like drift in the middle. Went down on the RHS and the crash bar took maybe half the impact and the bag the rest. Tore the lid off the bag, big dents, yada yada. THe pannier stayed on the frame and while the lid didn't actually fit and the lock tangs were straightened a little, it stayed together happily and I used a bit of gaffa tape to stop the water and dust getting into the bag again. Got home with all contents intact a few days later.
Have not yet tried panel beating the bags, but if you don't crash in them (only fall over trying to get up silly slippery hills and sideways across beaches and so on, imo you'll not have a problem with them.