I had a couple of FF diffs in my Sierra XR4x4, and they were excellent.
Any of these diffs can be scaled to fit into a model, that's the easy bit. What you can't scale is the Laws of Physics, and they start to give different results when things get bigger and smaller. Those results don't always mimic in a model car what is experienced in a full-size car. The clutch-style LSD might not work correctly when the area on the clutch plates gets to be so small, for example. An example of this is the size of dampers we use. If a TC damper were scaled up to a full-size touring car, it would be so big it wouldn't fit in the space provided, but if the touring car one was scaled down, it would have so little fluid and movement it wouldn't work at all in a TC!
That's the challenge, finding a solution that does what you want it to do. Simply looking to full size and trying to scale it is probably not what is needed. Something different is likely to succeed IMHO.