I recently read a description of Silverlines which described my the designer used dome mid-ranges. As I recall it had to do with a obtaining a more balanced on/off radiation pattern. It was in a review of the Silverline Sonata III if you care to look it up. FWIW
Are dome midrange better than cone designs?
I have noticed that companies like ATC and Audio Technology use a dome midrange. Is there and advantage to the dome design? It does not seem to be used much.