The hangers on my '03 appear to be made of some sort of silicone; prolly high temp (I have an incredible command of the obvious).
Sure, they allow quite a bit of movement of the exhaust system, but they isolate quite a bit of vibration.
The only plus I can see from using a harder material is to limit the movement of the exhaust system where larger piping or tips can contact the underbody heat shield and the rear bumper fascia.
If the car in question already has all three motor mounts made by an aftermarket supplier in urethane, then the added exhaust vibration is almost a non-issue.
But there goes any sense of refinement.
I like my liquid-filled ("tuned hydromounts") 2.3 PZEV motor mounts; those, plus added NVH-deadening material in my car results in an incredibly smooth feeling Focus. Quite a bit different than the '00's and '01's I've driven.
I've tried the urethane dogbone trans mount. I gave it three days and then put the OE trans mount right back on.