I'm in the "meh" camp. I like to keep panniers as far back as possible, and with the rack I use that means asymmetrical positions for mounting hooks. Plus, at least with my old Ortliebs the lower hook is always asymmetrical. So each of my rear Ortliebs only fits one side of the bike well. If I leave home with just one pannier, I grab one without checking. When I get to the bike, I see which pannier I took and just throw it on the rack.