Autotech also do their new wavetrac diff. Allegedly better than the Quaife.
A bit of reading for you.
http://forums.vwvortex.com/zerothread?id=3835523
Thats going to act more like a race plate diff, with ramps etc.. There angle is that there diff will always be engaged effectively, meaning that there is never a situation with low torque that you would find yourself spinning up the inside wheel..
The thing is that the whole reason I went for a Quaife diff was that under normal driving you dont have to constantly deal with the car wandering around, constant throttle, or off throttle it acts like an open diff, meaning that its very easy to cruise, ultimately not as fast to react as a plate diff.. but if you want to go with a plate diff do expect to be dealing with the consequences whenever your not on a billiard table smooth surface..
The ATB Quaife diff is certainly a compromise, but I know I would get bored of having a proper race diff in a road car