My "shim" was far more elegant, doesn't require butchering the cone, and achieved the same results. My beef with the 075 is not the high end roll off so much as the dip observed at ~9KHz. The dip removes both cymbol "splash" and well as intelligability.
The "elastomeric filter" can easily extend the FR of the 2405-diaphragmed 2402 well about 20KHz while further smoothing it out. There is a loss of few dB though.