Everyone's definition of light wind is different.
My light wind limits are:
90% of my sessions are below 8 knots.
My most used kite is 17m, at times it would not generate enough to stay up wind.
I do not own a LW ( 8kn and below) specific foilboard yet
Thinking about it.. i already kite a lot as it is in LW..how many more days would i be adding
I do ride a landboard occasionally on our hard packed sand at low tide when wind is E 4kn to 8kn
I ride landboard with my Core Riot LW XR3 19m2
When the wind picks up over 8kn it is time to get off the landboard and ride my Nugget 2013
So for me i would apply the same principle with a foilboard
I would only ride it with my 19 in sub 10 and get off of it as soon as the wind gets to be over 9kn
I am not interested in riding by rigging small kites for 10 kn and above using a foilboard
From what i have seen from those riding at our beach the advantage is in super low 5-6-7-8 kn
With 9kn at our beach that has nice shorebreak waves everyone has fun killing it on their surfboards
We are 5 at our beach with 19's
We enjoy smacking waves in shallow knee deep water close to shore
(i am not at all used to having to go chest deep to waterstart either