For sure i watch this space ...
I also watched all the frenchy spaces that discuss the windsurf foiling quite excessively.
The verdict there is:
The kitefoils (even using larger beginner wings) with their smaller wings produce not enough lift for windfoiling, because
a) the board/sail weight is higher than with a kiteboard
b) the sail does not deliver an upward lift, reducing rider weight, like a kite does
So for windfoiling there are dedicated wings now, having spans of 75 - 80 cm and areas of 800 - 900 sqcm.
E. g. the Ketos foil used for windfoiling with the biggest kitewing is rated as soso for lifting up early compared to dedicated windfoil wings. With higher speeds it works fine and is fast.
The foils used for SUP need to lift the board and the rider (no sail though), you got no upwind lift (or try using your paddel as a helicopter rotor), you can't produce speed like with a sail/kite, you won't reach speeds (usually) that limit larger wings like in kite/windfoiling.
The Videos of Naish and Starboard on the GoFoil show, that keeping the lift and the board in the air is the main issue in SUPfoiling.
The AHD Sealion Wings also uses the foil with huge wings designed for windfoiling and i can't see any turning/control problems in their videos SUPfoiling.
So my conclusion so far is, that higher lift windfoils would be better for SUPfoiling than the kitefoils.
I wonder if Alex Aguera is developping such a pair of larger wings for his GoFoil, that could then also be used for windfoiling.
To my mind the small foil Naish is offering now with its SUP is a not a good solution. I wouldn't buy that, but look for a windfoil like the Mantafoil with its high aspect wing (76cm span, 780 sqcm area)
Alex