I haven't had issue with buckles that attach panniers to the rack. I have had some of the plastic buckles break. I've also had more issue with the packer (drawstrings) than the roller versions.

I had a case where I was doored in Arequipa Peru. It split the pannier open. I found a shop that did suitcase repairs and they were able to patch/stitch together in a way that it still works for me now