Polyurethane sway bar bushings
 

Is there any point to choosing them over traditional rubber?

I know that for control arms it makes a difference, but is there any point to choose polyurethane for sway bars? not for the end links, but for mounting the sway bar itself

I think you're under the assumption that swaybars only "roll" in the bushings on one axis, which they don't. The same advantages poly has to rubber in other parts of the car applies to the swaybar mounts.

They do make a difference. Just depends if you want them or even need them. Keep them greased up to prevent squeeks if you go down that route.

For my Strut top bushings, I went with Whiteline which make rubber bushings but they are a much higher quality, thicker rubber. It's that halfway point between OEM rubber and poly.

So I assume that the urethane bushings increase the stiffness even further?

Poly is stiffer but it is known to bind so it depends on where you are using them. I prefer a harder than stock rubber compound over poly but that's just a personal preference.

Here's a good write/discussion up I came across a while back between the two.

Bushings: Rubber vs. Polyurethane - Subaru Impreza WRX STI Forums: IWSTI.com

Personally I've used both poly and rubber and unless it's on a car I'm going to track often, I would rather go with rubber. Overall it gives a slightly gentler ride (usually without any performance decrease) and there is less maintenance involved (as others have mentioned, you have to regrease [and ultimately disassemble/clean] the poly mounts at least once a year to prevent binding).

Is your car stock, stockish?
What future plans do you have for the car and what purposes will you have for the car?

What is the price difference between OEM rubber swaybar bushings and the aftermarket poly ones?

Think about how a swaybar works. When you corner, the car "rolls" to the outside. The job of the swaybar is to transfer weight from the outside back to the inside wheel try to limit the amount of roll. Stock rubber bushings flex more than the stiffer poly ones, so stiff bushings will make the bar more efficient. The difference is slight, might not even be noticeable for some people.

The swaybar bushings are dead on my QX4, but since I don't drive it like a race car, they are not noticeable at all till I hear them clunk from being worn out.

use teflon tape around the area of the bar the bushings will be touching, then grease over the teflon tape, u won't have any issues this way