Mark, I do respect your knowledge as a bowyer and know you have a few years on me in that realm, However have a hard time agreeing with that statement. Higher ring count means more late wood (denser cell structure) less early wood (lighter cell structure) So it's hard to imagine that a 30-40 RPI could be denser then a 60-70 RPI. Have you done any testing on your theory?
I do agree that elasticity is more important then density, but yew is so elastic in general, that in yew, I don't find this to be a problem.