Brining can bring flavor and even moisture to the bird, but the crucial part is resting the meat. For the birds in the freezer, just be sure to thaw them out a few days ahead of time and let them sit in the fridge for a few days to rest before cooking. Resting the bird in the fridge even makes grocery store birds taste better, in my experience, and they've usually been rested for a while anyway. And as Itsy pointed out, if you are processing an older bird or an egg laying breed for eating you are going to have to cook low and slow to keep it from drying out. That's why chicken and dumplings was so popular down on the farm back in the day. It's also why spent hens are called stewing hens. We processed three hens that were about a year and a half old this past fall ourselves. Two of the three were so skinny that they weren't good for much, but we made awesome stock and cut the leg quarters and breast meat away and made some delicious chicken tacos from that. The third was no cornish cross, but big enough that we tried roasting her. The dark meat was pretty good, but the breast was pretty dried out and that was even after brining for a few days. What we didn't eat that night (which was most of the bird actually) we chopped up and used in chicken and dumplings and it was much better the second time around.
