I Capuleti e i Montecchi at SF Opera: Bellini's opera I Capuleti e i montecchi had been performed exactly once at SF Opera before the run that opened last Saturday. As feature-length adaptation of the story of Romeo and Juliet, that makes it a notch more successful than, say, Gnomeo and Juliet. And a lot less than West Side Story, which will receives its first full concert by an orchestra with the SF Symphony in June. It's shocking. The delightful score by Bellini and the performance by the lead duo at Saturday's opening made an emphatic case for the opera to be heard on a more regular basis.