I just got one of these a few days ago. Haven't had a chance to use it yet, but it's definitely an interesting bit of kit. It looks and feels like what it is: a NOS 1800's era razor, with a substantial feel like a W&B or Wostenholm from that era. It's only 5/8 though, and despite the marketing copy it's definitely not a "singing" blade, it's more like 1/2 grind.
Mine had a hint of a frown near the toe, but a few minutes on the 4k gave it a proper smile that matches the rest of the blade. It seemed to take an edge very readily, I'll see how it goes tomorrow morning.