Most props have an rpm avoid range. It's a lot worse with aluminum than composite and a lot worse on a 4 than a 6, but it's still recommended with the composite to.The only reason I mention the impact damage is because it looks a lot like what I saw several years ago, but you probably have the better answer there, it's quite likely I'm out to lunch. I'm a bit curious about resonance being an issue, though?
You know, I've actually never heard of resonance being an issue on light airplanes that didn't have radials, you have any links about resonance on GA airplanes? I'd love to read more, I know it's an issue on the larger 4-bladed PT6s occasionally (I'm looking at you D model 1900), but never heard it being an issue on GA airplanes.
How the heck did you figure it out. Lol.