We did a head-to-head test with a Big Mama and a GK-Trix 15m at the L.A. Expo last summer and the Trix turned faster, went upwind better, and had more pull. This was a test in about 12-13mph with a 175lb. rider.
Upwind ability was obviously better from the shore, but turning, was what the rider, Mat Sweeting told me.
Give the Trix a try, you won't be disappointed. The review on http://www.sbckiteboard.com/2011-kite-review-display?news_id=1599
is a good one. Also ask any kite-repair person about the quality of construction compared to other kites.