And nobody has said this either:

Some 4cycles vibrate like crazy no matter how well the stuff you tighten onto their prop shafts is balanced. Truth is, if you can't sort out the vibration, sell the sucker to someone willing to believe that vibration ain't a big deal. We got a couple of guys at one field who will tell you that a certain brand of engines that're known to vibrate something awful are proof that vibrating is an indication of power. Amazing..... Find a dummy like that and sell the sucker to him.

Vibration kills crystals, receivers, servo gears, loosens bolts, screws up on-off switches, messes up connectors, foams fuel, walks out screws, and weakens glue joints.