I did find that my rear pannier's top rail got bent from the weight slightly. I think the extra hooks would eliminate that too.
Sure does! When I carry so much weight in food and water for my extended solo, self-supported journeys, it puts a lot of strain on the rails. I set one pair of hooks where I would if I used them alone, then distribute the other set for greater support. Works like a charm.
Also, if you have the older QL-2 hookset where the inserts are sometimes subject to loss, this addresses that problem as well. The later QL-2.1 hooks have a different design and so better retain the sizing shims.
I also run two sets of lower retention "fins" on *all* my Ortlieb panniers. As with the spare hook-sets, this makes for a ready-made set of spares already in place, but also does wonders to reduce pannier rattle on rough roads (though I still use compression straps). For my rear Thorn Expedition rack, I pair the lower fins together head-to head, fins sticking out fore and aft. This configuration catches nicely in the "V" formed by the bottom of the rack. One just lowers the bag in place and the two fins catch evenly between the uprights as the hooks snap into place.
I carry a spare wire for the handlebar bag mount, too.
Best,
Dan.