Point taken. Whenever period orchestras venture far beyond the Baroque, they have something to prove. But at last night’s concert of Wagner and Berlioz by the esteemed Orchestra of the Age of Enlightenment, some of the proof was self-evident. Banished completely are the intonation problems that plagued such ensembles in the past; one felt secure in the technical abilities of every section; the wind soloists played as expressively as anyone could wish. London is a center for period performance, which has become beloved. Sir Simon Rattle has conducted Act II of Tristan, in concert with the forces of Berlin and Vienna, but it’s good to be flexible, and since he enjoys a long-standing rapport with the OAE, they were a comfortable fit.