Advantages of beryllium?


Can someone please explain the advantages of beryllium drivers over titanium or aluminum?

Also, how concerning are health risks associated with beryllium?

many thanks for your input. 
defiantboomerang
shadorne, I dunno if what they say is accurate but it does seem to be a  pretty good summary - I'm not a dome kinda guy (Maggies) - tho if someone offered me a free pair of Sonus Faber Aida's I could be persuaded to switch.
@erik_squires 

Does the 936 have a Beryllium driver? Or is that reserved for higher up Focals?
Per the web site, it is Al/Mg.

Nothing against Al/Mg but Focal has this fetish for micro motors which are never as smooth or dynamic as the large motor variants.

Though lately ScanSpeak has produced some tweets which are close to the same motor size and very very good sounding.
I worry that people will accidentally stick their fingers into the tweeters of those precious Magicos…and according to at least one guy who sells them it seems that's not such rare a thing. My fragile aluminum-magnesium tweeters are covered by a mesh screen so have another drink cousin Shirley! Just don't knock the damn speakers over.