I agree with Donkey Doctor regarding lost power. I have argued this with others that insist that the energy absorbed by the flexing of a soft mount is "lost" energy, that you do not get back in power, but I still disagree with that viewpoint. I like the idea of using a soft mount on larger four-strokes (1.20 & up) due to their higher vibration. I even have a Saito .72 on a soft mount (Gator brand). I think a more rigid soft mount is better than a really flexible soft mount, though. Gator tells you to add silicone RTV to the grommets to stiffen them, if you so desire. Each engine/prop combo will vibrate differently, and what shakes like heck on one setup may be smooth on another setup.