Script Assertion or Groovy Test step when working with Request Output

I've read posts here on the forums of people using Selenium in groovy scripts, but I have not done that so I cannot begin to speak to it. I may be able to shed some light on the second option, though.

Here's a snippet that can parse a response for multiple Rate Factors.

import com.eviware.soapui.support.XmlHolder

def groovyUtils = new com.eviware.soapui.support.GroovyUtils( context );
def holder = groovyUtils.getXmlHolder( messageExchange.responseContentAsXml )

def nodeCount = holder["count(//*:e)"]

nodeCount = nodeCount.toInteger() 

log.info ("NodeCount: " + nodeCount);

def rateFactors = holder["//*:e/*:RateFactor"];

for (int i = 0; i < nodeCount; i++)
{
	// Process the data however you want
	log.info( rateFactors[i]);
}