That is my thought. I am from the SQL Server world and BizTalk is new to me, so I immediatly think to use DTS/SSIS. But I was trying stay to one technology and take advantage of BizTalk technologies like changing output formats easily and applying business rules. But in the sample runs I have done I see a 9 million row export taking well over a 2-3 hours in time and I have not even applied business rules yet in my orch.
I am running a single high end server, and was starting to wonder if BizTalk just can't handle that kind of volume. If a 100 messages a second is normal processing then I can use that as a base calculation… and show that even in doubling the throughput it still has a performance issue.