utility adapter cross reference table latency

Being new to webMethods, our company wishes to capitalize on cross reference table to overcome both the disparant key and echo problems. Would anyone using this technique please share with us the issues that you encountered with latency? Both good and bad would be appreciated.

Our system will consist of Siebel on a Solaris box talking with an AS400 native database (DB2). webMethods will also reside on the same Solaris box but the MS/SQL server cross reference table will live on an NT box within the same network.