But, I've never heard of this theory with concave and vacuum pulling your board off. I can't even imagine how that would happen, the board is cutting through the water, it is not acting like a flat suction cup.
With my initial rocker table design, I got out a board with pretty flat rocker in the middle, with bigger progression in the last quarter of the board. That's probably because of the concave shape. It was very wide in the center and finished around the place where the tip rocker started to progress. Depth was 4 mm. There was little transition from flat bottom to concave. When the board was lying down it seated flat on the concave edge.
So if the board was lying on the flat water it took a lot of force to lift her by the handle, so it was acting like a suction cup. This also showed when jumping, specially in low wind, when you pop less and the board lies flatter on the water surface.