The basic problem with Polys is that most bushes on rangies are "metalistic" ie the rotation of the bush is handled by the rubber giving elasticity in 'shear' . The metal parts of the bush do not rotate. The only rotation is absorbed by the rubber. This is why they can be limiting to articulation.
Poly bushes rely on rotation of the centre metal sleeve against the poly bush. Add dust and sand, and they last a very short time. They do not generally have dust and sand in Europe, although they do have mud.
I had a Panhard bush set get about 1MM play around the centre sleeve from one trip from Sydney to Peoppel Corner and back.
regards Philip A
