Diamond drivers

Johnk, not sure what you're driving at. The crossover, driver, and cab work are all part of the essential the design work, although some may argue that the crossover is the most important.

Dracule1 no I report it as I hear it. Sure home editions could change the outcome, but I heard enough of them in enough rooms with different equipment to base my own conclusions. I have been at enough shows to get a basic flavor for things. It is how I hear it and I am not discouraging anyone from listening on their own. They are not my cup of tea.

Okay. I've heard them at shows myself and haven't been impressed either. But get them in a proper audio room, and the sound can be transformative.

Diamond tweeters are for real. While they do make for good marketing and unfortunate price increases, they deliver.
I have owned the following loudspeakers over the last ten years: B&W CDM1, CDM2SE, CDM1NT (Aluminium tweeters), Jamo Concert 8 and 11 (Silk dome tweeters), 804S (Aluminium tweeter), 803D and 803Diamond (Diamond tweeters).
As context for my observations: I am very sensitive to any tweeter harshness.
I like the silk dome tweeters, but not so much Aluminium dome tweeters - they tend to have a residual metallic sound. The better Aluminium versions will only occasionally highlight a distortion artefact, as opposed the less accomplished versions which are almost unbearable after a few minutes.
However the diamond tweeters are clearly superior: better transient response, cleaner, more precise sound-staging, transparent to quality of recording and audio equipment, consistent sound quality across their frequency span. And yet they are easy on the ears - I can listen for hours without fatigue to the 803D and 803Diamond loudspeakers.
I have heard many other loudspeakers at dealers with different tweeter technologies including Beryllium and Ribbon. I haven't heard anything at dealer that would indicate an obvious weakness with the B&W Diamond tweeters. However, as always, a definitive comparison will require extended home auditions.

You are right about the pleasant sound of the Diamond tweeters. But there is more than only the tweeters. The biggest problem B&W has is that they still not make great filters. Wenn you do a test for depth and how wide the stage is, B&W is quite poor. This was the main reasson why I did not want to continue with B&W. I owned the 802N and 800S. The new series still have this problem. Depth ann a wide stage are one of the most excitings parts of highend audio. Wenn this is not that exeptional good, you miss a lot of excitement during listening to your favorite music.