"minus" still ought to work and perform OK if the query can read indexes, even if functions are applied to the values ... have you validated that indexes are being used instead of FTS? Do you know what proportion of your total load time is taken up with the minus ops?
Sure....We have two instance of each table. One is trunc-reload daily and the other a pseudo history table which is insert only. There is a huge push to implement async-CDC shortly so that we load only deltas. Our team is not in the loop as it is not seen as DBA related !!
Promise me you wont laugh at this. All the descriptive columns are NOT NULL. So they default to a single space. These minus queries are written with trim and NVL functions...so though we have proper indexes in place most of the time the queries perform badly....The list goes on...