this is speaking from personal experience, not just experience driving the car to work and back everyday, but someone that has deliberately abused the hell out of their car for fun.
I cannot talk highly enough of the factory torsen diff that comes in your import jza70 lsd. it has proven in excess of consistent, reliable, smooth and fun. In the 5 years of ownership It has slipped into a single spinner mode not once but twice. otherwise it puts power down to both wheels every time and paints 2 lines every time.
I have seen them break and will totally agree every time that they are not suited to drag racing regardless of power or tyre, but for every other form of driving I have participated in, I couldnt have asked for any other diff.
I have since moved to a KAAZ 2 way lsd (since i want to continue drag racing) and this diff has delivered an expereince almost on the complete opposite end of the scale.
The breaking in period is a complete nightmare, the diffs behaviour during this period is offensive to say the least. The noise, the clunking, the harshness is really out there. Then you have the whole new driving experience when locked to get acustomed to. You no longer have any security from mistakes on the road (from kerbs) and it takes time to get used to.
Once the diff is broken in it becomes tolerable but I personaly question its performance vs practicality compared to the torsen.
The 2way is an all out ballsy drifters diff with no manners, but will offer far more benefits than a torsen, however for a factory diff, teh torsen is a champion.
the above views are of my opinion and do not neccessarily reflect every torsen out there. If there are manufacturing faults with these diffs or different people have different experiences I totally accept that.
/2c