You'll have to call GOODE on that one..........
What size XT were you on and what size Flextail did you try? Who set it up for you? Remember your binding placement numbers and fin settings? There were two distinctive "variations" that worked well, and lots of people spent time chasing settings that didn't work as well. My ski worked really well with either of the settings that were somewhat common place for the test team to be on. I love my flextail, but see the positives of this Rev6 helping lots more people fall in love with the ski.