@a773 It will certainly be compatible at a theoretical software and hardware level. It's not going to be directly compatible at a mechanical level though because the new board is shaped differently. It's significantly smaller than the main section of the original core. The IO test points are necessarily laid out differently to fit into that smaller space.
I'm guessing that there will be a straightforward way to attach the new core to the bottom of the existing axo control and make it work. We could even design a physical adapter if there is enough demand. I don't have an axo control on hand to test at the moment. If someone wants to send me one, I will look into making it work as smoothly as possible.