I used some of the cooked crabapples in apple bread yesterday and the results were really good. I had initially added 1 cup of sugar to about 6 quarts of spiced crapapple butter. I personally thought they were still pretty tart, bordering on sour, although my son loved it.
The apple bread recipe I used called for 1 cup of sugar per loaf. Generally, I think that makes a loaf that is too sweet but in this case the proportions were just right. I'm excited about future crapapple endevours!