I've got one hard mounted in a Prestige, after all its electric with no vibration! What I have since learned however is the two advantages to soft mounting are noise reduction and a theoretical longer gear box life since there is some ‘give’ with each impulse of the motor.

I have no idea where it’s at sound level wise, but it definitely makes some noise on the ground. In the air, it only seems to be a little louder than the outrunner…I can still fly in the early morning hours without disturbing the neighbors.