strad wrote:I don't know about the Haldex but the Torsen is great and seamless.
Torsen does have issues with slip where very low to zero load occurs on one drive wheel. During this they act basically as an open diff, sending sending all torque to the one lifted wheel. As such they require a degree of resistance (traction) to work effectively to enable them to see a torque bias across the driven wheels and distribute torque accordingly.
That is where a locked diff, Haldex or plate diff works much better as it does not require both wheel have load (traction) to provide drive. One wheel can have large slip values such as where one is lifted off the road surface into the air or there is on a very low friction surface (ice, mud, water, oil, dirt etc).
There is a hybrid diff from Wavetrac diffs that are a modified Torsen unit which uses a ramped friction surface to overcome the traditional Torsen short comings by engaging when there is a drive substantial differential between the driven wheels.