beryllium vs diamond

Sound better, or sound more accurate? The latter is whatever is lightest and stiffest, i.e. diamonds.  I have beryllium.  It is fine. I listen to good music, not to equipment.  

This does nothing to settle anything on the issue of course, but as a matter of pure anecdote:

I recently auditioned the Paradigm F3 with it's beryllium drivers against the B&W 803D3 (diamond tweeter) in the same room on the same equipment.

For me the high end frequencies of the B&W were much nicer, a more beautiful sense of harmonic richness, distinction and clarity to cymbals and other high frequency elements.   The Paradigm sounded somewhat opaque in comparison.

I was surprised as I've never been a big fan of the B&W speakers.

Okay have to laugh at this one never heard a Beryillium midrange sound opaque.

It depends on the rep, over the years we have worked with many factory reps that were clueless. 

What was the gear running the 7F?

The 7F and especially 9H sounded super crystal clear and transparent to me. Both with moon gear. They were only out done in detail, imaging and clarity by the Magico M2 and Tidal Contriva G2. These speakers costs far more.