I've seen the seal on my 22" kettle change over time. Using the hinge it no longer sits flat as it did when I installed the hinge. Probably because the metal is thin and easy too deform, and grill temperatures are high. If I pull the pin out it'll sit flat otherwise all kinds of smoke comes out of it when I put the lid down while grilling. Notice while grilling it doesn't matter to me so I haven't worried about it.
My intuition says the hunsaker hinge is superior because of this it doesn't need to be pinned to work. It's basically a guide that holds the lid up when you want it up but it's free-floating at least up and down when you lower it
On my wsm where seal is important.... I'm still not convinced to hinge is a good thing to put there. That and i also need to access the back side to spritz food evenly etc. And having a lid there simply interferes. Just a hook to hang the lid on is sufficient.