I just got done putting some poly bushings on my '06 GTO. I have used poly bushings in a few cars over the years and love them. I have seen some misconceptions here, so will add my two cents.
Poly doesn't deflect as much as rubber, so will give better handling.
Poly tends to "flow". This means that over time, it will deform. With sway bars, just check on them and tighten them after a few months, that's all.
Noise- yes, they CAN make noise. They don't squeek. Rather, they can make a creaking sound. The ones on my '96 Impala (a arm bushings) sound like an old mattress when it is freezing. But, sway bar bushings should be quiet if done right.
Some say that using grease will make them quiet. Yes and no. Any grease will make them quiet, but for a short time. Then they get noisy. The ONLY grease that should be used (write this down, kiddos!) that should be used is Energy Suspension teflon polyurethane grease. This will keep them quiet for years. It is thick, sticky stuff. It is pricey (around $5 for a couple of spoonfuls, plenty for sway bars), but it is awesome stuff. I even use it on interior plastic pieces (like door panals) to eliminate squeeking.
So, go ahead and get the poly bushings and install with the grease. Oh, and while poly can help the handling of the car in other areas immensely, keep in mind that there are huge differences in the quality of poly from different manufactors (hardness, noise, etc).