Just throwing out some things to stir the pot...
Consider the differences between rubber and poly bushings. Rubber will deflect more, which helps to absorb bumps. Poly is stiffer, which will help to hold the proper alignment under stress, which will improve performance.
Now...take a look at the design of the lower front A-arm. Notice that the front of the A-arm is straight, and the back angles steeply to the back of the car. This means that the alignment is controlled by the front bushing...and the rear bushing takes all of the stress of bumps.
See where I am going with this? If you do Poly in the front, and rubber in the rear, theory states that you get the best of both worlds with minimal negatives. Of course, this is theory until someone does it. I intended to do it when I rebuilt the convertible suspension a couple years ago...but through a miscommunication, the outer bushing casing was removed from both the front and back, forcing me to go with rubber for the entire lower arm. So I am running rubber for the entire lower a-arm, and poly everywhere else. I am very happy with the way it rides, and don't notice any extra noise or harshness from the rebuild.
Like I said....just stirring the pot. I can't really suggest that you jump into this head first when it is only theory.
Edit to add: I am still using stock WS6 springs with KYB shocks and struts.