Glad you like it! This guy has been in development for nearly a year, and I'm really glad to have it available finally. Web page just went up with in-depth manual, block diagram, etc. and it's in stock:
Thanks Teej! It tracks well on guitar, though the standard pitch tracking disclaimers apply - it'll track better with the tone rolled off on the guitar, plucking with the thumb instead of pick, etc. For the adventurous, lots of interesting effects to be had with intentionally glitching out the tracking with unison bends, double stops, arpeggios, and so on. It definitely tracks better and across a wider range (down to low B on bass, relevant for the super-downtuned guitar guys) than most similar synth and octave pedals.
Yep, FV1, although I'll note that the pitch tracking algorithm is significantly refined and improved compared to the more simplistic code that Don has distributed freely in the past.