I have four KC Ducks, 3 female and1 male and they seem really happy. I also have a large number of chickens, roosters included, and they pretty much ignore each other for the most part. Sometimes the Drake will chase the roosters away when they mount a hen though (Duck chases chicken away from chicken)
I normally have a positive experience with Murray Mcmurray but have never ordered ducks from them (can't be shipped to my state)
I ordered cayuga hatching eggs once and 2/3rds arrived broken or 'scrambled' inside but they were packed very well so I can't imagine how they got that bad unless the ride was very rough.
Never had a problem with ordering chicks from MMM till this year. I ordered early because I wanted some very specific chicks and they were going fast. They finally ship and I wait...and wait...and wait...four very cold days later I get a call that they've arrived but there is no noise in the box. As you can imagine there were no survivors. It was really heartbreaking. The hatchery replaced the order but you still feel terrible about the little ones that didn't make it.