I believe with the MultEQ XT you get upto 8 measurements and better filters. From their website...
"MultEQ XT, using the receiver interface, takes up to 8 measurements around the listening area and uses high resolution equalization filters for satellites and subwoofers. This is the most powerful built-in version of MultEQ for receivers."
"MultEQ takes up to 6 room position measurements, and uses mid-level resolution filters for satellites and subwoofers. "