On my boat we see the difference between up and down to even more of an extreme because there is no keel and we can completely raise the centerboard downwind (but rolling is different, as it more closely follows wave surface in a multihull due to form stability). The narrow hulls provide directional stability even with the board raised.

When deep reaching I will usually raise the centerboard to deliberately induce more leeway and take a course lower than the heading would indicate. We generally don't go DDW in light air because deep reaching is faster, so unless the wind is strong we tack downwind when we have room.

I've never determined whether it's faster (in terms of VMG) to raise the centerboard and "crab" downwind or to keep it lowered for better tracking and more SOG but higher/longer course. Anyone have thoughts about this?