Let me first say that I am anti-polly bushings so your not going to get a sales pitch from me. i think polly bushings are a commercialized product that everybody wants becasue it sounds cool to say and they read the ads in their Hot Rod magazine. I would only replace my bushings with Moog problem solvers for a normal use vehicle. The newer polly bushings have adapted anti-sqeek materials int their bushings so they dont start squaking nearly as soon as they used to. BUT....they still dry out prematurely as compared to the newer high durameter rubber bushings.
Keiths car has a welded frame, complete polly bushing kit every freakin where and the car rides as stiff as a board. We need to soften it up and p[lan to do so by using Moogs.
I'll make this point clear, if you already have polly bushings or can get a good deal on some arms that already have them installed and yours are toast, fine, use them. As long as you grease them regularly with the correct polly based grease, they will last for quite some time.