I'm researching this topic as I'm a firm believer that anything that rotates needs to be balanced due to less wear & tear, less structural stress, & increased rpm. I started balancing or at least checking props while I was only running two strokes & APC's were a good choice that seldom needed any adjustment, since then I've ventured off into 4 strokes, grabbed the correct prop for engine break-in, and I had so much vibration @ say 1/3 throttle & less, I thought the horizontal stab was going to snap. So I'm looking at balancing props alot closer now on these 4 strokes (this being my first). I fashioned a crude balancer from 2 faucet washers (new) beveled ends toward the prop & poked a piece of radio antenna though the washers, I have the radio antenna ends supported on two pieces of angle aluminum (inverted) & the prop swings through, between the rails. After looking at the post above, it looks about like the "finger balancer" mentioned.