Yogurt as a Substitute for Butter

I've had great success baking with no-fat, plain yogurt instead of butter. Baking powder biscuits, spice cake, bread, muffins; everything's turned out great thus far. Butter isn't necessarily bad for us. I remember my grandfather slathering it on his toast and he lived to be a ripe old age. On the other hand, he was a farmer and worked very hard physically. Few of us put out that kind of effort on a daily basis.