You mentioned cayugas looking like mallards? I think you have them confused with rouens. Cayugas are completely black: bill, feet, feathers. They are very good layers, mine matches my pekins egg for egg.
I have pekins, rouens, and cayugas, and none of them are really 'skittish'. They will take off like a bat out of heck when the puppies get too close, but the pups are always chasing them too, so they know to be on the look-out.
All three of these breeds will lay an egg every day during laying season. I have one pekin that I assume is a bit older than the others, she lays for 3-4 days then takes a day off. But still, I get 5 eggs a week from her at least, and 6-7 from each of the other ones.
These are some of my ducks. In the back is the rouen hen duck, the two black ones are the cayugas, the multi colored one is a rouen drake, and the whites are the pekins.
I love them all, and could never decide between one breed!