I ordered eggs that carry SSC from a hatchery. I hatched 3 double factor silvers aka “lethal whites” in the group, they are partial albinos, with purply eyes and pure white feathers that are thinner than regular, they look more like skim milk color than whole milk if that makes sense. They have a lot of issues and live inside because of their thinner feathers.
As far as lethal goes, 100% of their eggs that I put in my incubator developed at least to lockdown, right now the first batch are hatching and one has hatched fine so far. However I matched them to regular pearls, so no double silvers. My advice is to keep only one gender of silver per pen, in order to prevent having to keep quail inside because you or your family get attached to the adorable little yellow chicks.
However, if you like white meat, I found that the double silvers have much lighter meat. I’ve been testing hatching them because I want to produce some light meat birds to eat.