How close a reproduction is the Pi-Phase mk2 compared to the original Mu-Tron Bi-Phase?

We believe that the Pi-Phase mk2 is as close a reproduction of the original pedal as it's possible to achieve in the modern day. By reference to the original schematics, and with knowledge draw from ownership and use of two Bi-Phases (and a Mu-Tron Phasor II), it was possible to design a more compact version of the original. It was decided to incorporate the foot-switching directly into the pedal itself so the Pi-Phase mk2 would be usable on it's own with no need for external devices / pedal-pedal switches.
The Pi-Phase mk2, like the original, features all-analog LFOs and audio sections, and through-hole components for the critical parts (the LED and LDR coupling section). 1% tolerance metal film resistors were used instead of the original carbon types so as to reduce noise. The +/-15V internal power supply design was retained, as this is a big part of the high-headroom / clean sound.
A great deal of experimentation was done with the optical phasing section, so as to match as closely as possible the response and sound of the original pedal. Anecdotal comments from users of the Pi-phase mk2 comparing their pedal to an original Bi-Phase range from '95% of the way there' to 'identical in sound and function'. Allowing for sentimentality and considering the price and availability of the Pi-Phase mk2, this is a result we are pleased with.