I am pretty sure Dave and me are talking the ultimate lowest wind possible to hydrofoil in, when you can not go upwind.
Which is lower than when you can start, say 5-6 knots you can start in, because once you are going you can keep on till you make a mistake in a tack or jibe or similar or even just when turning it is "the end" of course, no matter how good you are.
In this wind, maybe 3-4 knots ? the most efficient foils and efficient wings (and size too) is of utmost importance, if you want to be able to hold ground because of pinching the window as said.
Lighter kites are better and easier to handle yes, but I would still say that efficiency (high AR and apparent wind power and high L/D) can ride in the lightest winds, even if a tad heavier
High efficiency low weight is the best, but not easy to find - and the difference isnt a real gamechanger for (m)any, as most wont ride in winds where you can not stop without having to loop yourself back to shore (or a swim).
If there are some small puffs though, one can ride in less average wind than you can start, thus the overall efficiency is important to be able to hold ground as said.
The problem with these threads are, that we dont know if we are talking about the "same" low end, as numbers are almost useless.
Half a knot or one knot difference in wind makes it from impossible to more than okay, or from possible to easy - so we might be discussing apples and oranges here, without knowing
We should be out on the same day same wind same spot all of us, in 3-6 knots of wind, to compare this ultimate low end