I'm going to recommend the "pointer" method since we had that scenario presented to us in a Deep Dive / Ranger training last year. It makes sense since otherwise it is a complete waste of bandwidth and resources to push those files into and out of SQL Server, not to mention moving that data over the wire twice more than would be required otherwise. Even if SQL is on the same Dedicated BizTalk Server, now its a resource and performance issue you shouldn't need.
That would be a great project to work on and then test performance against the original app and current BizTalk application.