The Kyosho gear diffs are in testing before they go into production.
As always Kyosho make sure its all good before massive production.
I have tested lots with Durango diffs and on high grip its a benefit but with the Kyosho proto-types the car is much better.
I do feel the car with ball diffs can be easier to drive though
I know someone is going to ask me when but unfortunately I can't answer apart from soon hopefully - LOL