An interesting read about these bushes, the topic is all about the quality of replacement bushes, even the ones from SAIC are not holding up as they should as far as I can see, a supplier changes from manufacturer to manufacturer on price dependency and the quality will invariably suffer so it seems a bit of pot luck when buying.
For proven quality I think going down the Powerflex route would be the best policy, there is minimal pricing difference and I know that the old bushes have to be pressed out and the poly bushes pressed in but to a competent diy mechanic there is nothing scary in that, a garage would happily fit these bushes if supplied.
The purists may not agree but when we have to keep replacing bushes and links because of poor quality then another solution has to be looked at, I have recently fitted Powerflex anti roll bar bushes to the front of my ZT, I just wished they made them for the rear too.
Here is a link to the Powerflex bushes.
Powerflex