I heard the $4000 Focal Utopia Headphones yesterday

Don't jump to any conclusion. If you have the means and are interested, give it an audition and decide if it's worth it to you. I did just that, after half an hour of listening to music of different genres, I bought it. And I already own the $3,000 Hifiman HE1000. Substantial step up. 

Lots of paranoia around here. The effect of any poison is dependent on the specific compound involved and dose along with the frequency and duration of exposure. For example, many old houses contain asbestos, but there is no particular risk if the material is stable and not disturbed. It is when the material is removed that things become hazardous unless special precautions are taken. 

Here's a link to the CDC web site on beryllium: https://www.atsdr.cdc.gov/csem/csem.asp?csem=5&po=15

And, just to make everyone extra paranoid, don't forget that apple seeds contain cyanide and solanine can be found in potato skins.

One things for sure that sexy carbon frame cost a small fortune to make,
not to mention that is lighter and stronger then steel.

It’s the dust that’s toxic as all hell. Focal staff wear rubber gloves, airway protection, face shields, and medical gowns when they make the diaphragms. Once they’re in the tweeter they're fine. Just don’t go smashing it and snorting the dust.

Parts Connexion is having a significant sale on Stax headphones.

Pure Be is diff. than alloys. Pure Be is brittle as hell. Break it and the dust is toxic if inhaled.