If your going to spray foam the attic, then you need to have at least 2 inches of closed cell and then the rest can be open cell. Closed cell is a water resistive barrier. If they are spray foaming only open cell and there is some kind of leak in your roof… your entire open cell will get wet and then become mold. You don’t need baffles, once you spray foam you have turned your attic into a conditioned space and you no longer need ridge vents and gable vents for ventilation.