Good point. It depends on what you use your xj for. This worked great for me when I needed 4wd in the snow and still had decent handling, as well as increased traction when offroad. Some call it a more "aggressive" limited slip. If you are looking for 100% lockup all the time, this isn't exactly what you want.
i ran 2 true tracs. i hated them . id rather be open or locked up front, the thing never gave me traction when I really needed it. the lockright up front makes all the difference in the world.