I've heard that before but I thought that it applied only to citrus. My hens always get fallen apples from a local orchard and I've never noticed a difference in the rate of eggs that I get.
I use SS all the time and couldn't get any better production. My leghorns produce 6 out of 6 most days of the week but even on an off day I get 5 out of 6. My BO are just starting but so far they are very consistent even for an average egg producing breed.
My white leghorns and BO free-range in the afternoon when its not raining. So far leghorns are doing great on range, they are fast, chase cats and small dogs. However, I have lost 2 BO to a fox.