Thanks, yes I had a look inside - two big PCBs stacked together covered with bits and bobs!
I like the sound of the filter side, but as it sounds like a band pass (which I prefer for the quack) it needs dry below it too. The octave/synth side is great actually, and works fine currently. I've never been a huge fan of octaves but this one sounds really musical and the synth/fuzz that you can add in gives it a bit of a unique bite.
I've downloaded your C4 patches and will give those a try later!