coleman wrote:my edge 11m is a handful in 20+ on the foil.
I'm not sure they are recommending 11m in 20 kt with HF. That would not be much fun for an average HF kiter.
9m foil kite may not be a bad choice for you, especially if your local conditions are typically puffy, so you can use stronger gusts to get you going. If your friend is doing well with 10m Speed, you should do as well with Chrono 9m once you master it.
Pick the size that you will need the most. If there are more days of less than 10 kts, get 11m.
I use 11m FS Sonic for the low end, but I do like to down size to 9m at around 12-13 kts. If the wind is 9 to 11 when I start, I usually go straight to 9m (27m lines). It is just more fun for me. I used 9m race LEI, now I bought 9m Pansh A15 foil kite that I find more user friendly. It was a bargain and works well. Like you, I can't budget in 2 pricey foil kites