Downsidesdelicate, easily overdriven, higher distortion, beaming dispersion pattern. Ribbon and quasi-ribbon also exhibit edge resonances and a rising frequency response, some more than others, making them difficult to work with and listen to. However, these traits are attractive to aging boomer ears with hearing loss.
why aren't ribbon tweeters more popular?
What is the downside to ribbon tweeters? I haven't had any in a long time (Phase Linear P580's, stolen, still miss them.) Ribbons offer great extension and speed; other than expense, what objectionable qualities limit their use?