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Make a difference in what? How the car handles? NO! Poly bumpers probably will give a somewhat harsher jolt, than would stock bumpers when you buttom out. Poly bumpers may last longer, but in my judgement, rubber is good enough for a control arm bumper/stop.
These bumpers are an integral part of the suspension and were designed to work in conjunction with the factory springs. Even if you feel the need to replace the bushings with plastic, I'd be inclined to keep the rubber bumpers.