I've substituted quail eggs (1/4 cup of quail eggs, 7 eggs, for one large chicken egg) in baking when I've run out of chicken eggs. They are richer and the cake came out much more dense and moist.
I don't really believe all of what was said in that article. As JJ said, no one has reported allergies to quail eggs, but how many people have actually eaten a quail egg? Versus how many people have eaten chicken eggs and have documented allergies?
Feed plays a big role in the egg's content. In mass produced chicken eggs, I would think the egg content is much poorer than a home raised chicken that gets to free range on grass and bugs over a large area. Commercial free ranged chickens are just raised too dense for the area to get as much benefit as home raised. Also, there's those eggs that are marketed with added nutrients. They just add them to the chicken feed.
I was just recently officially diagnosed with an egg allergy. I've had a hunch that I've been allergic to eggs but ignored it for 35+ years! Basically, cooked or eggs used in baking are fine. I just don't eat them runny or raw. Or have more than 2 at a time. I do have Eggs Benedict once in a while (yum!) and deal with the consequences. It's so worth it.
Too much of anything is a bad thing. My husband sees kids who drink too much milk and get anemic (the calcium starts affecting iron uptake). Parents who cut out all fat in their kids foods and affect their development (fat is needed for brain development and kids are growing!).
I always thought that eggs were the "perfect" food since they contain all the different amino acids. I haven't check that out, but they are the "perfect" food for chicks!