Okay, it seems that the single skins works fine, but not the same power and smooth performance as some of the other contenders:
Racekites in the light versions - but they turn a bit slow because of higher AR usually, and seem to "fold" easier.
Concept Air Pulsion light version.
Aeros Navy2 Ultralight version.
Aeros new prototype coming up ?
Ozone Hyperlink UltraLight, max size 12 m2 though.
Pansh Aurora 2 Ultralight ? - if true it is heavier than the Hyperlink in std cloth, it is not a true marginal wind kite...
Flysurfer soul, a contender too or not as light ?
Regarding how low you can go, numbers are only a rough estimate and not really useable - so it is experience and comparisons neck and neck that matters
If the 18-19-21 m2 kites can go a tad earlier, but at a cost in terms of agility - one must decide what is preferred.
I dont read any experience with the Aeros Navy2 kites ???