The second switch is only useful if you want speed gonging and to be able to scroll through the menu backward. (You don't need either of these features.)
Speed gonging is probably the most useless thing Porsche has ever thought of. It allows you to set a speed, then when you reach it the car will beep. You don't need it, and it isn't worth the extra $35 for the second switch.
Also, I don't think you can get the OBC stalk without getting the cruise control stalk too even if you can't hook it up to anything.
