I finally received my PCB!
Unfortunately I found 2 bugs on the board revision I sent for production but it was too late, so there are a few small straps on it.
Anyway, I soldered all the components, did a bit of debugging and it finally worked, all 6 voices!
It works quite fine actually, better than on breadboard. Eg. the potentiometers ADC captured lots of noise while on breadboard which made adjusting values hard. Here the noise usually doesn't exceed 1 bit.
Overall much less noise on the PCB, which make the VCAs really quiet when closed.
Pic of the board (sorry, cellphone quality):
(The heatsink is temporary, I will use the case itself as a heatsink.)
Now I just need mount the board inside the case, solder the connectors (I have yet to receive them) and the synth will be done :)