that's an interesting idea, however I think you'll find two main obstacles:
- finding PCB mount banana jack sockets that fit the same layout as the jacks the PCB is designed for can be tricky. I had a quick look on RS and could not find any!
- banana jacks - as far as I understand - don't allow normalled connection. Now, on Pepper the pots are normalled through the CV in jack to a voltage reference that allows the pot to work on its own when there is no signal plugged in, and to work as an attenuator when a signal is connected. By removing that normalled connection (as you'd have to do for banana jacks), you will end up having the pots not working when no CV input is plugged in.
If you could find a switched banana jack of the right PCB footprint (and assuming you enlarge the hole on the faceplate), then you could possibly give it a try. If it was me, I would just get a bunch of 3.5mmjack-to-banana cables .