Over the years I have done a bunch of cars with them.
I have them in my 63 Belvedere now. Yes you will feel more vibration over rubber.
Now my car has no under coat or any insulation of any kind.Was to be a drag car but now is street only.I had a poly transmission mount in it too but swapped
it out for rubber to lessen the vibration.Other than that they are good to use. Well maybe not on a Chrysler Imperial.