In his time he enjoyed a reputation ________.
句意:在他那个时期,即便谈不上比莫扎特还伟大,他也享有与其齐名的声誉。此处将主语与莫扎特进行比较,比较级需要有than构成。if not greater than部分为插入语,要表达“和莫扎特一样伟大”要用as great as Mozart。因此,本题的正确答案为B。