I don't know the answer to your question but I'd like to add to it if you don't mind. What does the center diff do?
The center diff distributes power to the front and rear differentials. On a diffbrain model it is unlocked completely or locked completely. On a non diffbrain model it is always unlocked.
Unlocked sends WAY to much power to the front wheels, locked distributes power 50/50.
I'm contemplating taking all the servos out as the sweet spot is somewhere between, but I figured I'd start with just the front and rear.
The diffbrain is a novel idea, but for most people unnecessary