Bushings have very little to do with the ride in reality. The ride quality is defined by the tire sidewalls, torsion bars, springs, and shocks.
On the front, in particular, contact with the road by the wheel is at the end of the control arms and is absorbed by the torsion bars and the shocks. The bushings are the pivot point and even if they were at a direct impact point, the thinness of either the rubber or the poly bushings means that transmitted shock is almost the same.
In the rear, they are a bit more in the line of impact being at the ends of the leaf springs but it is still a minimal effect given the sliding action of the leafs and the damping of the shocks.
What I have noticed over the years is that the poly seems to transmit more ride noise than do the rubbber bushings...I think the higher durometer conducts the higher frequencies better into the frame and is carried into the car as a result. I suspect this, along with a tighter, more reactive steering feeling contributes to the feeling that they ride harsher due to less give and a truer movement of the parts-less deflection
Of course, when a worn out rubber bushing is replaced by either rubber or poly, the front end will be tighter and this may contribute to the harsher perceived ride because nothing is floating around.
