Yep all good advice from above. Although I would temper savages opinion on wind ranges. The bow kites may have had a great wind range but I still maintain the sweet spot was smaller.
The 11m edges wind range is enormous and the sweet spot between my three boards is a moving target. Its all about board selection and what mood you are in. My ideal sweet spot is 17 to 23 on a mako 140 at 75kg, if I'm in a crazy pumped up mood that moves from 19 to 25. On the king it is between 14 and 18. On the skim between 11 and 14.
Your winds sound similar to where I kite, my bro is 80 odd kilos and the 11m is used 70 percent of the time.
My ideal quiver would be 17, 15, 13, 11, 9, and 7 edge....a 14, 12, 10, 8 cat.....and 6 REO
And a 10m NRG liquid force,
With a 130 monk and a 150 mako added to my board quiver...
Sweet spot heaven....see where I am going with this....