We always eat our extra roos, and the occasional hen that meets a bad end, i.e., dog, fox, car, etc., (I've had 3 hens get hit by cars this summer) and is found quickly enough that the meat's fresh, I dress them out, too. If they're over about 14 weeks they'll be tough, the older they are, the tougher they are.
But, if you cook them in a crock pot, pressure can, or cook slowly for 4 or 5 hours in the oven, say in a cooking bag or some dish with plenty of moisture, the meat's then tender and delicious. The broth is dark and rich, makes wonderful gravy, sauce, or soup. You can't beat an older bird for flavor, especially heritage breeds.
You can use the meat in all kinds of dishes, I favor Mexican mostly, enchiladas, tamales, burritos, tacos, but you can use them anyway you like, and they'll be yummy. Dumplings, soup, pasta dishes, pot pie, BBQ sandwiches, chicken salad, whatever. I've even added the meat from crock pot chicken to fried potatoes with onioins, and made hash, it was great.
True, they won't have the huge breast like the Cornish X, but the flavor's better. IMO, the healthier the bird, the better it will be for you when you eat it. The non-meat breeds are healthier birds.
There are people currently breeding various crosses to come up with something in between, a bird that reaches a good butcher weight around 5 lbs. or better at 10-12 weeks, (rather than 6-8 weeks) still young enough for a fryer, but more active than the Cornish X's, better foragers, therefor presumably healthier birds. The hope is for birds that can live well past butchering age without the leg problems or CHF (congestive heart failure) that the Cornish crosses are prone to. The ideal bird would have better flavor as well. C. X's are a bit bland, for my tastes. I've raised them, and will gladly eat them, but I'm aware of their shortcomings, too, and would like to raise something better.