They definitely can't be feather sexed, but according to one of my books they can be sexed by down color. The male's tops of their wings will be a lighter yellow than the females who have darker red colored shoulders. It also says the females will generally be a darker red color. I'm not sure how accurate this is, but it worked for my five heritages. It seemed to me that the differences in wing color became more distinct with age.
This technique is also strain related as to it's "success". Some strains present with the lighter wing patch on the males and some strains do not, so it's only so/so on effectiveness and is strain dependent.
Again, if you're a breeder of these birds, you could care less. You find out for certain at around 8 weeks anyhow, so just feed them, water them and enjoy the ride. There's no real need to know any sooner, unless you want backyard pet egg layers, in which case these standard bred birds aren't likely the right choice anyhow.
I agree that over the years, the odds are pretty dang close to 50/50.