Hi Jim,
I replaced all* of my bushings with the yellow poly bushings. In my driving, I have found that while the yellows are quite stiff, I feel they give a great feel of the road, and I still get a very comfortable ride from the car.
My Poly Bushings do squeak quite a bit, but I believe that the shop who pressed them in for me either didn't grease them, or didn't grease them enough, however, depending on how you drive, they might not be to noticeable. When my stereo is on, I don't hear them at all, and when the windows are open, I only hear them when I am not going "fast" ("fast" being >35mph). They also seem to be getting quieter as they wear in, or I'm so used to the noise that I don't notice it anymore
All that is of course, dependent on how you drive, and how you want your car to perform. Roads and Suspension travel may make substantial difference
I had bad bushings in the rear (my car had a rough life before I got it) and a bent parallel link, so I replaced the bushings since I had the car apart, I likely didn't *need* to, but hey, I had the kit.
~TEck
*I didn't replace the bushings in the rear hubs, as I didn't have anything to take the hubs out with. I know that OT recently did a set of these bushings as well, and he had a trick to doing the hubs while they were on the car, but I can't remember what it was of the top of my head!