Tonfarbe,
I think you did a great job on the pedal, and it sounded excellent in the clips you did. I think, though, that it sounds much more like a Tubescreamer than a Zendrive (there's absolutely nothing wrong with that... I dig Tubescreamers
). From your clips, it just doesn't seem to have the Zendrive's pronounced snarl or "chirp," which is what really separates the Zen from most other pedals. I'd be curious to hear clips if you ever get a chance to A/B the two pedals in a direct comparison.
Anyway, thanks for sharing your project with us, and I'm looking forward to seeing what you build next!