My motor was balanced so I can’t speak for the vibrations, my stock motor LMM vibrates pretty good, so I could see it being an issue with a stock motor, but I personally prefer the solid mounts.
I bolted both mounts on my LLY when it was stock and it was ok, I just did the driver side on my LMM because my dumb ass was tired and in a hurry put one of the bolts too close to the center for the passenger side mount and it wouldn’t fit, so I get a lot of movement still, I have another mount but only time I have issues is in 4x4 going up steep hills around the house.