On another thread IWB2 says his sweet spot on Hyperlink 7 is 14-18. Rides it 12-22.
Sounds about right to me. I think the top end for me is a little higher on foil and quite a lot higher on surfboard and twin tip. 7 is my most used kite, though at the moment I've been switching between 5 and 9 to seek low and high end. I think one of the lessons of hydrofoil is that there is a lot of overlap in kite size in force 4 winds. There was a video where BRM Greg rode tiny and big kites all in the same session.
Seems like I need a 6m. Perhaps a Soul??
I'm very curious to fly a Soul. They look stunning and I have been quite happy with my FS.
I would be careful about commenting sizes between different manufactures. Some manufacturers over or under state size e.g. 8.6 and 9.4 might both be called a "9" Also some kite generate more power for size by flying fast, others more static pull. Flysurfer had a trend seeking to extend top end range of their kites between the Psycho 4-Speed 3/4. With Speed 1 I could fly my 7 when people were on 13 Waroos. With Psycho 3 I was on a 10 for the same range. (Psycho3 10 was one of my favorite all time kites) With Psycho 4 I had a 12 and I would say the bottom end was similar to a 10 meter tube kite, but the sudden spike in lift it could make by flying fast was awesome for big jumps. Speed 4 DLX was also underpowered for its size but could make a crazy power spike if looped into the window. Speed 4 lotus came back a little in power for size where I would fly a 10 compared to 12 tube kites. I would venture to say the HL-7 is a little more powerful than Speed 4 lotus 8 but I don't have the luxury of flying them back to back. I actually purchased the HL-9 to replace the Lotus 8 when I lost it in a crash. I was quite surprised with the bottom end power of the HL. HL-9 definitely has more pull than the Lotus 10 which I still have. However the Lotus turns better when depowered, resulting in better use in the top end wind range. Lotus is more resistant to folding a wingtip into the bridle when carelessly riding downwind. I would guess I could get higher jumps and a harder yank off the water with a TT and the Lotus. The Lotus has better relaunch, but requires foil kite technique to reverse both rear lines. The active wingtips on the Lotus make it a little more difficult to body drag out in light winds.
Hyperlink and S4 Lotus are very different kites. Both gave me a lot of fun. Soul is a new generation for FS. I would not guess how the Soul is based on my experience with Hyperlink or the S4 Lotus.