I recently put Truetracs in my T100 too (front and rear) when I swapped to 4.56's from 4.88's (anyone want to buy my 4.88 diffs?). They're defintely better than open diffs, but nothing compared to lockers offroad. I haven't played with them offroad a whole lot yet though since this isn't my wheeling rig, but I did mess around enough to notice the difference. If off-road performance was my goal, I'd defintely have gone with lockers though. There is just no comparison. My goal was good street/snow traction and a little bit of improvement offroad compared to stock.

And on-road the rear truetrac works well to keep that inside tire from peeling out when pulling out of a corner in a hurry, especially when things are wet or slippery. The rear Tundra LSD I had worked well too until the clutches wore out... which is why I decided to swap to the Truetracs.