Both, I guess. I have a friend's PackRat and I'm trying to figure out if I like the so-called Wave Cannon option JHS put in there. That's most likely based on Mk I since everything else inside is a Rat derivative.
From Josh Scott on the PackRat Mode switch. 8. Caroline (2010)
A few years after starting JHS, I purchased a fascinating distortion pedal from a brand new company out of South Carolina. I remember jumping on the phone and geeking out with the designer and head of the company Philippe Herndon. We talked about the circuit, his love for RATs and his clever take on the circuit. That pedal was called the Wave Cannon and when I started the PackRat project, it was obvious that Philippe was the friend I should bring along for the ride.
Yeah, I read the manual. I was rebuffed the last time I asked JHS for a schematic. Apparently it is not their policy to share schematics, even if they are 99% based on the work of others.