what works best in an AutoX/road course setup is highly dependant on the car, drive train layout and speeds at which the car will reach.
for EG:
Any Porsche we build for track purposes, Solo1 or any type of racing where high speed corners in higher gears are encountered, we run plate-type LSDs. on say an AutoX or street driven Porsche we'll suggest or run a ATB(Torsen/Quaife).
again, depending on the driving you are doing one dif will always be limited in a certain area.
if you look at a lot of the drift guys, cornering speeds are not that high but most of them use a plate-type dif to get lockup so they can break both wheels away equally. some may even run Spools but that's beside the point.
with plate type difs you can alter the dif-action under things like accel, coast and i think decel(i'm not the guy who handles dif setup here) again to suit the type of driving you are doing.
in the focus world, simply because there are no serious plate-type difs on the market as an option, everyone just defaults between the quaife and the torsen. imho, neither is better nor worse than the other. like everything, people try ONE thing and then preach that it's the "bee's Knee's". the people who have driven both in a high performance situation may not but usually can tell there is little difference between the 2 all testing being equal which is why a lot of people opt for the "cheaper price or lifetime warranty" angle.
having built and driven Focus' with both quaifes and torsens, i really don't see a difference in how they work between the 2, just in how they allow cars to power out of corners vs a stock diff. i'll install which ever the customer wants but wont suggest one over the other... i opt-out for the "cheaper price, lifetime warranty" angle, and let the customer choose!
i know some places push one over the other but usually that's simply a profit margin reason or they don't carry the other and want you to buy a LSD from THEM!
