I have used poly lower control arm bushings in my cars for tens of thousands of miles. When I replaced them with the Delrin bushings that are in my Duster now, the poly bushings looked brand new still. All of my sway bar bushings are poly, I've never had an issue with them at all.
Like everything else, they have to be properly installed and lubricated in order to function properly. At the LCA this is especially important, they MUST fit tightly into the bushing shell. It's almost a light press fit when they're right. And unlike rubber bushings, then need to be greased. In some locations they can be greased on install, but at the LCA even if they're well greased on install eventually they'll need to be re-lubricated. Which is why I use greaseable LCA pins.
You wouldn't throw I giant lumpy cam into an engine with stock valve springs. If you use aftermarket parts, you have to make sure your car is equipped to use them. Not just slap them in and hope for the best. Poly bushings are different than rubber, you can't treat them like rubber bushings. If you install and maintain them like poly bushings, they'll outlast rubber every time.
If a set of poly bushings failed in a couple of seasons, they were improperly installed. Period. I've installed dozens and dozens of poly bushings in multiple different vehicles, I've never had a failure. The poly LCA bushings I pulled out of my Duster after 10k miles looked identical to the day I installed them.
