Do I need a dropper post for gravel racing?

It depends on your courses. For flat to rolling races with no technical descents, a rigid post saves weight and is fine. For races with steep, loose descents (like many Colorado or Pacific Northwest events), a dropper post dramatically improves confidence and control. Many top gravel racers now run droppers even on relatively non-technical courses because the descending confidence gain outweighs the 200–400g weight penalty. If you're on the fence, try one — most riders who try a dropper never go back.