I have seen this light wind debate in wind foiling and one thing I noticed is it seems not all wind is the same.

Perhaps this has to do with wind meters not always being accurate depending on wind direction, or maybe land features speeding up the wind on the water, or slowing it down at the wind meter.

At some location kites will fly at a wind speed where other locations they will drop.

So, when you say you want to Wing Foil in 5 or 6 knots, I believe at some locations that is possible, at other locations it is not, and it might have to do with the way the wind meter reports the wind, or the chop on the water, or how steady the wind is, or something else.

At my location once the gust is under 10 knots no ones goes out. In a 12 knot gust my Swing 6 works on a large Infinity 84 foil. In an 11 knot gust it might work with a lot of pumping. Keep in mind these are the gusts, not the average.