According to Rick (the torsen guy), quaife's lsd is capable of biasing upto 63% while the torsen unit is designed to bias upto 71%.
He also mentioned the torsen unit as possibly being more durable...allegedly their design makes the gears less prone to "tipping" within the bores they ride in.
Durability concerns are probably not a big issue with either the quaife or the torsen...but since the prices are similar i'd take the torsen for the extra traction it may be able to provide. i think...
