SSIS Advantages

This may be too general a question but I'm going to ask it anyway.

I'm moving data from a source DB (say A) to a target DB (say B). On A I need to join 3 tables and, after some lookups etc., I need to populate several tables in B. Inserting into B's tables involves sequential operations because in many cases I have to get back the value of an Identity column to use as in input value in a another table 'downstream'. Additionally, the tables in B are populated as a group i.e. if the insert on any one fails the entire group's insertion needs to be rolled back.

I set up a set of stored procedures to do this. The master Stored Proc opens a read-only cursor and for each row of the cursor executes the other SPs in proper sequence. Some of the SPs are 'enclosed' within a transaction to enable a Rollback on the group.

My major concern with this approach was the 'known' inefficiency of the cursor and the huge memory requirement it's use would entail (the cursor would pull about 15 million rows).

So I began looking into SSIS thinking it would be able manage the system resources aspect effectively and offer better performance overall. I've realized, however, that even in SSIS I would essentially need to first pull the 14 mil rows into a memory-resident object (or a temp table - whose benefit I'm not convinced of or haven't fully understood) before looping through each row to perform the data inserts into B.

So, is there any real advantage to this over the first approach ? Perhaps I haven't looked deep enough or wide enough. Any constructive suggestions / feedback would be highly appreciated.

Thanks.