I am also curious about what "torque-biasing center diff" means.
Here's the screenshot from the Traxxas webpage:
Based on the text at the bottom, it just seems like a regular center diff filled with heavy fluid. I think I saw somewhere that the 6780 has 1M weight diff oil, which is very heavy for a truck this size. While I do prefer center diffs myself, I am not sure there is a big performance gain here over a slipper.