I noticed that too. My engineering eye says... the vertical male/female mating ridge is further from the hinge pin than before, and longer contact length, thus will be able to resist torsional forces through the hinge better, and stay tighter, than their traditional side-hinge joint. Jaws, and then New Jaws, was supposed to be even better, as the hinge pin was only to hold the two frame halves together when folding, so when unfolded, all forces go through the tapered jaw teeth (external on Jaws and internal on New Jaws). I don't know if they have abandoned New Jaws, I think it's still on their premium models, but this new hinge on the Mariner appears from photos to be an improvement, but I don't know for sure. It's also aluminum, which is softer and wears faster than the steel hinge on my old Dahon Speed. Oh, but it also has a Deltech cable, that will reduce bending stress on the hinge and improve durability a bunch. My improvised deltech did so on my bike. Deltech does not, itself, take any torsional load, but by tightening the hinge (it does by loading in compression shear), it improves torsional stiffness there, rock solid when standing climbing.