I blew up the T-lock the very first day I owned my 84 GT, back in 87...and that was with TRX wheels and tires, lol
Went to an Auburn cone clutch unit and autocrossed/lapped with this setup (4.10 gear) for about 20 yrs and 200 000 miles. Sold the unit used for $100 after that, still works fine today.
Way better than the t lock, predictable in the wet coming out of corners, smooth.
New build has 8.8 axle, 3.73 gears, 31spl Mosers, girdle, welded tubes, and MM T/A and PHB.
Oh...and a Truetrac unit from Summit Racing, running 315/35 Nitto NT01's. Have done a bunch of track days as well as about 20 passes at the strip;
car hooks up like Velcro, and the rear end is quiet. Needs conventional 85W140 dino gear lube, NOT synthetic. The improvement over the Auburn is as great as the step from the Tlock to the Auburn. There is Zero lag time between applying the throttle and getting real traction coming out of a corner or in a straight line (ask the dude in the Gallardo what my tail lights look like lol). This is both in the dry, and even more confidence inspiring in the wet. Catching a slide is easier, as is regaining traction when the rear end breaks loose under hard braking (prior to T/A install).
No question one of the best mods possible if you drive the car hard out of corners or launch. There is some extra axle end play compared to the other diffs I've had; may have to machine up some spacers, since I just installed manual brakes, will see this spring.
Now - the diff between the various Torque Sensing diffs - TrueTrac was bought out by Eaton, and their quality issues seem to have been taken care of. They also make a tougher version with 4 side gears instead of the more common 3 gear version which is even stronger. The tech discussions on the bias ratios lead me to believe that it is a small (potential)improvement for a lot of additional money. The actual friction/weight bias increase is fairly small, IIRC; the spring loaded setup likely cuts down on the reaction time, especially during suspension loading and unloading.
Having said that, the only real and fair comparison would be to swap out the diffs in the same car and try all 5 different models. My belief is the torque sensing concept is a big win (Audi, Quaiffe, etc) and we are likely splitting hairs between all these products.
Locating your axle properly (if you have IRS then the Full Tilt Boogie credit app should be filled out)and using real dampers and tires will likely overshadow any differences between the various TS diffs. I am a fan in a big way, that's for sure.