I would love the choice to be able to choose whether wrong answers are deductive or not. The point of partial credit (especially in elementary school) is to give PART credit for correct answers.
Example: If there are two right answers on a MC question. If the student gets one of the choices correct and one wrong, and under the partial credit, it would give the correct answer one point and the wrong answer would subtract a point. The student would still end up with zero. So there is no point in choosing partial credit because whether they got one right or one wrong, it still is a zero- which defeats the entire idea that there will be partial credit.