Hello gentlemen (and possible ladies). I put down some thoughts on the OneBlade design elsewhere and realized it would be relevant here, as well. I'm thinking through the design of this razor and some of why it performs as well as it does.
Apart from the pivot, what stands out to me in the OneBlade design is the idiosyncratic shape of the head. Rather than a curved top and typically thin safety bar, the razor's cutting area is described by flat planes above and below the blade. Those angled planes create the "registration surface," as OneBlade calls it (for all I know, that's the term in razor design generally). The razor very naturally uses that surface as its contact plane on the skin. It's very intuitive, and because it's a fixed angle, the rest of the blade geometry (exposure, angle) can be kept exactly where the designers intended it. I think this is a big reason the OneBlade cuts as comfortably, effectively, and consistently as it does.
Thinking about it, other razors either allow for many more angles (these tend to be "aggressive" razors), most of which are sub-optimal and so invite cuts or irritation; or they do indeed only really cut at the "correct," most-effective angle (the Feather AS-D2, or the DE89), which makes them much less damaging (folks say "mild") but still require the user to maintain that angle. So for most DE razors it's a matter of: lose the angle and the shave is uncomfortable/damaging (aggressive razors), or lose the angle and the razor isn't cutting (mild designs). Either way, you need to learn and keep the angle.
The OneBlade does this for you by, yes, offering just the one optimized angle where the razor will cut whiskers, but making that angle very, very easy to achieve due to the "registration surface."
Another razor that comes to mind thinking about this is the Merkur Progress, which in its way makes the best angle pretty easy to find, due to the way the head is designed (there's quite a well-stated registration surface with it, in part because of its wide, flat safety bar).
David : DE shaving since Nov 2014. Nowadays giving in to the single-edge siren call.