I hear you. I'm using Silvolites in my build with stock rods to retain the somewhat original balance. Did all the weight measures and they are pretty darn close. No balancing for this cat.
My son does a lot of race engines here . You would not believe the power difference in an engine when the balance is perfect.
Some over 9000 RPM's and they feel like an electric motor.
Harmonics really slow things up. Put a slightly bent pulley on an electric motor and see what happens. It will never reach advertised RPM's
I was down in the shop tonight and my son was balancing a 500 inch new Molnar BB race crank. I took a video tonight. You would not believe How far it was out and how much you could feel it in the Balancer. He is going to cut the counter weights down alot and rebalance it I'll start a thread to show the difference. He was chucking it up in the lathe when I walked up.