LOL it cracks me up (no offense) how hard you're making it to sex a duck. To me, it's easier than sexing a chicken
But if the quacks are confusing, just go w/getting one of each, but yes it sound slike 2 boys & 4 girls, so you'll leave your friend w/1 boy & 3 girls, so that'll be one happy boy
Also, a pair can get along just fine, but a trio/quad is idea. I have a quad of rouens and that is perfect.
As far as the whispering...from what I gather the whispering/hissing is more of a muscovy thing. The males of other breeds still quack, but it's hoarse is the best way you described it. I'll have to read tomorrow on how the vetn sexing goes and now tomorrow I want to go try that on my 6 exhibition rouens I have!
Best of luck. I LOVED my pekins when I had them, but as far as raising them in mass quantity to sell it just wasn't practical $$$ wise. But for pets, they were awesome!
Kristi