Are you referencing the new non-metallic tweeters showing up in Wilson speakers?  I've found that materials dictate the resultant tone of the sound they reproduce and nothing get's cymbals right like a metal dome.  Berrylium, paper, silk etc just don't ring with the correct overtones and shimmer.  Diamond aint bad, but I liked the inverted Titanium tweeters Wilson has used in the past compared to the overly polite and smoothed out trendy tweeters being implemented now.