The task of matching a conductor to an orchestra is far more complex than merely identifying a high level of skill in each. Orchestras, as well as conductors, often have distinct personalities, and a conductor who goes over fabulously in, say, Cleveland, may not get such a warm reception in Boston or Chicago. So when the St. Louis Symphony Orchestra announced David Robertson as its next music director, the real question wasn’t whether either party had the necessary skills for top-notch performances, but whether this would be a match of musical personalities. The SLSO played New York with its music director-designate this week, and Bernard Holland found the new marriage promising.