I just tried my new 08 14mtr Rhino on the weekend, IT ROCKS. Heaps of power in around 15-18 knots. I weigh 105kg and hope my new 14 will replace my 07 16mtr torch. Not sure how it will go under 15 knots but i recon it will be fine. Maybe you should look at a new light wind board instead of a new kite. Much cheaper.
cheers.