It seems to me that a jibing board will operate at the same angle of attack as a conventional board. The reason is that the leeway will increase until the board produces enough lift to match the loads applied by the rig, and the contribution of the hull at low leeway angles is probably small compared to the board and rudder. The board is going through the water with essentially the same orientation whether it is jibing or not, because it still needs the same angle of attack to produce a similar force.

So what you're really doing is rotating the hull relative to the board. This has implications above and below the waterline.

If the hull is generating a significant amount of lift, this load will be shifted to the board, which should be able to carry it with less drag than the hull, due to the much greater span of the board. However, if all the hull lift is eliminated, this reduces the effective span of the board to being the same as its physical span. So there's a benefit to having the hull carry some of the load, as long as it doesn't cause flow separation or shift the lateral balance and increase the rudder trim drag. From a lift-induced drag point of view, the optimum hull load would result in the wake coming off the hull being deflected sideways at the same angle as the wake coming off the board. You want the whole vortex wake shed into the water to behave as if it were a rigid sheet along the whole span from waterline to board tip.

Obviously, it's hard to determine just what amount of lift this is without a very sophisticated calculation or test program that takes into account the board, hull, and free surface.

I suspect the greater effect of a jibing board comes from the rig rather than hydrodynamic effects. Rotating the hull makes it act like a ballestron boom. This opens up the angle between foretriangle and the apparent wind, effect