I haven't personally driven a car with the other set up. But i have the pan hard bar and torque arm set up on my car. The rear end is solid. Plants to the ground very nicely. And if you want to kick it out, you can do so at will, and even if you want to play with the back end out it is very easy. I can roast the tires through 2nd gear and let go of the steering wheel and it shoots straight as an arrow.
I did a staggered style slalom over the weekend and i had some fun with it. One run you basically could have considered drifting lol.
I would say it is well worth it. Just make sure you have appropriate front suspension also. Since the rear end is really solid i now have a bunch of understeer due to the factory K member and A arms.
It is a corner carving set up, so keep that in mind. If corners are your goal then definitely ditch the 4 link.