I haven't tried mine yet. By engaging the pivot do you mean going past the 30/45 degree angle normally suggested before you make the pass? The pivot doesn't seem to kick in very easily if I just bring it out to a 30degree angle.
From the videos I've watched, they recommend you keep the head flat against your face (which I assume puts the blade at the optimal angle). Engaging the spring mechanism by lifting the handle ensures the head is flat against your face but doesn't apply excessive pressure. Often when I lifted the razor off my face the spring would audibly snap the head back. I hope this makes sense, a bit hard to explain. Keep in mind I have only used the OneBlade once so I'm sure I'll learn more as I go.
I was pretty aggressive and quick in my shave to see if it lived up to the hype and it did. At a minimum, I could see this being my travel razor. I'll get some more time with it this week. I really hope OneBlade rethinks it's blade strategy because I think they have the start of something good here.