As you can see, I'm not Tiesda. But I would like to give you my point of view.
Considering that the only variable is the board, as you start to point upper and upper, your speed decreeses and then you loose planning and later the fin stops working and you slide to the side. So a board which is able to keep planing in lower speeds will be able to point higher. And wider boards can plan in lower winds. So you have already my answer.