Bulk Insert Task was the most preferred way to do large bulk loads in DTS because it takes advantage of the performance gains using the T-SQL BULK INSERT command. With Integration Services, however, it is recommended to use the Data Flow Task. The Data Flow Task has numerous advantages over the Bulk Insert Task, which has rigid limitations on how it can consume and insert data. The Data Flow Task can bulk load data with comparable performance, especially if using the SQL Server Destination Adapter, while providing much more flexibility.

The Bulk Insert Task is a wrapper task around the T-SQL Bulk Insert statement. The task generates the Bulk Insert statement from the properties set on the task and then sends it to the server where it will be executed. Therefore, all the limitations that apply to the Bulk Insert T-SQL statement also apply to the Bulk Insert Task. 

Because the Data Flow Task replaces the features provided by the Bulk Insert Task, it is recommended to use the Data Flow Task for bulk-loading scenarios. The Data Flow Task is easier to set up, just as performant for straight bulk inserts, and more flexible.