It's easy enough to get at the AMF response from a Groovy script using the getXmlHolder method..
Simply use the responseAsXML property instead of the response property:
E.G.
def groovyUtils = new com.eviware.soapui.support.GroovyUtilsPro( context )
def response = groovyUtils.getXmlHolder( "amf-request-get-contacts#responseAsXML" )
def quota = response.getNodeValue("//object-array[1]/flex.messaging.io.amf.ASObject[1]/map[1]/string[8]")
What I like to do from there is save the property to a properties step:
def props = testRunner.testCase.getTestStepByName("properties")
def user_quota = props.setPropertyValue("quota", quota);
And then set up the AMF request's method argument to evaluate to the property:
${properties#quota}
If the AMF request needs an object for the method argument, you can grab responseAsXML contents via the AMF step's from the script editor.
