We've sailed a B423 in light winds and were very happy with its performance. 8-9 knots of wind, the boat sailed 4.5+ or so. Not bad. (Took off under gennaker.) I've heard that the B473 is great in 12+ knots but a complete dog under 10 knots and not even worth sailing. The numbers don't make sense. Just asking those with direct experience with the B473, how's she in light winds?