Can't tell you as 2 years ago used my old strutless 9 m². And I think it is more about the question if low AR foil kites have the ability to drift better, while also being better upwind at a certain mixer trim. I could imagine yes, but you have to compare the LEI you prefer 1:1 and it will always stay different as a foil kites will never flutter what a strutless does when depowered to much.
I think I (64 kg) can ride the 4,5 m² in about 12 knts, just check the video of the first start and when the wind drops and I should stay with fun up to 35 knts gusts. It doesn't have a wide range for a foil kite, but it is good for a kite with such low AR. But it is also much about my very low drag hydrofoil, so depends a lot from this. Tried these days my old full race foil from 2016/17 and it just felt draggy . So maybe you will need 15 knts or more with a normal foil.
@irwe: Should be 23 m of flying lines, but I think to go about 3 m shorter in the future. And sorry haven't tried the 6,5 m²