Some vehicles, and it depends entirely on the vehicle will vibrate after even the smallest of lifts.
I would recommend checking out the rear pinion angles, but if your going to do more with the motor mount lift it may be 'putting the cart before the horse'.
Do all the suspension work that you plan on doing (for a while), then check out your angles. At least it'll save you the efforts of correcting it all, then having to do it again.