Still important to balance the prop to minimize the vibration you DO get. Donkey Dr. is dead on. Have you ever watched a full size small plane start up (172, J-3 etc)? You'd think the engine was falling off it's mounts as it first fires up. I figure ours are about the same. I use a DuBro anti vibe mount, you can wiggle the prop hub about 3-5 mm in any direction, but I doubt it has this great an excursion with the engine running, though. I can tell a difference when I pick up the running plane with the anti vibe mount as compared to my ARF with a solid mount. Both are running comparable Saitos (.56-solid mount, .65-anti vibe). But go with what you're comfortable with. I doubt that whatever power losses there are, if any, are significant enough to matter.