No, little vibration at low RPM. I have late Alfetta rear rubber coupling. The only drawback of the front (aluminum - not steel) coupling is that it is relatively heavy. I think I weighed it at some point to compare to a stock front coupling, but I don't recall the numbers. I spent a lot of time aligning the engine output with the transaxle input, resulting in the 1 cm spacers at the Milano transaxle front cross member being removed completely. I also modified the engine rear, transaxle rear, and transaxle side mounts to make them more stiff - got the recipe from Al Mitchell using polyurethane. The transaxle side mounts were cross drilled and bolted - OD of bolt slightly smaller than diameter of drill - standard by many.
Jes