A competitive review document was released by Lustratus Research Limited which compared the SOA appliances from 3 mayor vendors:
1. IBM Datapower Appliance
2. Layer 7
3. Intel Expressway
See report below for more information on the result of the independent study:
Gamal Metwally
Thys Michels Blog 
This report has clearly been commissioned by IBM. The “facts” on the other two products are either blatant lies, or are based on extremely outdated information.