What you're looking for is Muscovy Ducks. The males get about 12lbs in 12 weeks, the females to about 4.5-5lbs after 10 weeks. They have excellent feed-conversion-ratio, they're good forages, they're practically silent, and they raise their own young. The meat texture is closer to beef than chicken, they're leaner than other breeds of ducks. In fact, if you grill muscovy breast fillets like steak, it will taste almost identical to a nice steak.
Personally, I find I eat about 1/2 the amount of duck meat vs chicken meat in a meal and I'm satisfied because it's a much richer meat. In fact, google says 100grams of duck meat is 337 calories, whereas 100 grams of chicken is 239.
The downsides are: plucking waterfowl is more of a process, and the poop. They poop a lot.