the loose boards (and also the park) have a lot of flex.
that means the rocker-line increases with the pressure. that's rally cool, because more rocker makes the board slower and better controllable in high wind conditions.
when you ride in choppy water, the flex shows some disadvantages - i can also imagine that you can't pop into big airs out that good with a flexing board.
the loose AX boards go upwind automatically when there's enough pressure for flex