The current project I am involved is using BizTalk 2004. Due to stringent latency requirement against large volume, we have decided to go without BizTalk.
I would like to see a global configuration facility in BizTalk that instructs not to persist anything while doing transfermations or orchestration — even with an atomic / long running scope. This would certainly be a risky proposition yet it would improve response time a lot. Wishful thinking!
Here are a couple of great articles on how to reuse BizTalk maps in .Net app.