hi Robert,
>>>>Could I use SAP Web Dispatcher to route the calls for a specific interface to the decentralised AAE?
I believe you can use it for this purpose but I'm not a web dispatcher expert so you need to check with basis guys - then should know for sure,
http://help.sap.com/saphelp_nwpi711/helpdata/en/48/99ac3a7f020e27e10000000a421937/content.htm
Regards,
Michal Krawczyk