Okay! After reading through this again, I do have some additional questions -

1. I'm assuming the cartridge bearings are replaceable - where can one find drop-in replacements?
2. Are you seeing any additional wear, especially on the top bearing, from having the torque/load of the downward force on the handlebars and stem transfer to the bearing? The way my brain is processing it...on a normal quill stem, the load from body weight follows this path: handlebars --> stem --> steerer (usually steel) --> headset. On your design, it is handlebars --> stem ---> upper headset cap. Just curious. I can see how it can be immensely more stable and stiff, but my brain keeps thinking about that 'push down' force directly against the top headset cap.
3. Is the bolt steel, and the wedge aluminum?
4. Any info on country of origin?

Thanks!