Hi!
It seems to me that comparing AppScan to soapUI is going to be a bit like comparing apples and pears since they are used for testing different types of applications/components; they seem to be more of a complement to each other than competitors in an enterprise testing setup. What you could do is compare AppScan to the web-application testing possibilities in PushToTest (
http://www.pushtotest.com), which includes both soapUI and web-application testing with tools like Selenium, etc.
Does that make sense and sound reasonable to you?
regards!
/Ole
eviware.com