Supposed to be better but only real world use can tell you that.
I will fit the silver/black ones to the top of the diff & the orange/red (one with the bar through it) for the front support, waiting till after Xmas when the $$ are back.
They are more expensive then the factory ones, 2 to 3 times more expensive! But if they are as good as they claim & you have changed these before you will happily pay the difference. Prick if a job.
I have been told that it stiffens up the front end improving power transfer (less movement means power is transferred to the wheels more efficiently)
The negative is supposed to be more vibration can be transferred due to the rubber compound not absorbing as much as stock ones. Reports from the American SRT8 forums is no different to slightly more vibration.
http://www.cherokeesrt8.com/forums/a.../t-150402.html
The reason to replace them is not so much the knocking & excessive movement that you get when they fail but the pinion alignment with the front prop shaft, alignment issues are the main reason the boot fails on the CV in the end causing CV failure
I replaced all the diff bush's with factory ones & the CV, I still had a CV failure 30,000km later.