The only thing that I'm still not sure is what happens to the data inside the pic32 chip.
I'll have a look, but my guess is that it's a simple UART>USB that can be replaced by CP2102 or similar cheap chips.
If I'm right, the USB to UART replacement board that will allow plugging the hashing board to a PC/Raspberry or any controller with USB would probably cost no more than 6-8$, but you will need one for each hashing board.
Dedicated "hub" up to 4 boards should cost 15-20$ using a single chip.

All the hashing chips I've seen so far are working the same for the data, it's UART to USB. Made by different chips, usually depending on what you want to do.
CP2102 and similar simply carry the hashing data. <- what we are looking for with this project.

PIC are used to allow monitoring and dynamic change of voltage in some designs.

I have a few AT90USB162 boards that can be reprogrammed as UART to USB. It could be fun.
MR3020 > USB-UART converter > hashing board

MR3020 should be able to handle the same firmware the hashing board uses, worst case, it would need minor changes.
Once it works, a cgminer build with the correct parameters should allow cross platfom use.

Now, back to work on something else while waiting for the S1 to arrive tomorrow.