I for one LOVE duck eggs. Richer yolks, more so than other straight from the small farm eggs and of course SIGNIFICANTLY more so vs cheap store bought. I DO NOT think they are magical of course.
To be fair if the average fool is eating 5 eggs a day from walmart and he suddenly starts eating 5 duck eggs in their place they will see gains. I say this as most average people are NOT going to account for the difference in macros, more fats and proteins, and if we are talking a young guy/gal they are likely undereating so the the straight swapping one for one MAY give them the surplus their "IG ABS above all else diet" is not giving them.
TLDR: Duck eggs bigger, bigger is better.
Don't tell anyone, and B-boy and Luki will verify this if they really really trust you: The "secret" is...........................ostrich eggs(there the biggest,) you can thank me later.