Lewis, a few years ago I bought a new pair of Ortliebs, Classics this time. The first ones were Pluses, the ones with the lighter material, and the old ones are just about 20 years old now. In all those years, I always picked them up using the "release" strap, I never thought it was good for the bag material to pick them up by the straps. In any case, 20 yrs on, they are still used my myself or my son, and never had anything go wrong with them, come loose or whatever (I take that back, Ive broken the plastic buckles by shutting them in car doors a few times, but simply bought replacement buckles at an outdoor store)
Because of their longevity, and a REI sale, I decided to stick with Ortliebs and get a new pair, figuring they are pretty darn good value over the long term. There are lots of good pannier companies out there, but I still like the Ortlieb system-I havent had experience losing the little doohickies, but I could see that if in rough rough conditions like the couple you mentioned (the lawyers right?) it would just be easier to make the rack tubes thicker, as mentioned by someone. So far, so good for me in fairly light commuting use with a bit of touring thrown in.