I think this is actually a lot easier than people are making out. Just need to develop a formula and maybe give it a nice user friendly interface.
For instance in a drop down menu a user could select their experience (A) 1: New, 2:Intermediate, 3:Experienced. (B): Input Approx Weight, © Size of Kite/Make
Based on this info it could output a more accurate wind range suitable for flying in. I'd be happy to work on it if people can provide the info and experience, then it can be finetuned over time.