I got my "Storey's" book yesterday!!! Looked up angelwing and protein, he does recommend no more than 18% from 0-2, and 16% up to 10 wks, there is no recommendation beyond that.
It says "IN GENERAL, diets containing more than 16% protein greatly increase chance of wing disorder." Ducklings raised outside with access to swimming and lots of exercise don't tend to have problems.
I think for now I'm going to keep food as is, but it has been such nice weather lately I'm going to start putting them outside for just a little bit during the warmest part of the day so they can forage and get some exercise. They were out yesterday and didn't want to come back in! lol