You can roast, but from personal experience, the older the bird, the tougher the skin, and I've not found a way to get it good like a young CX - I can cook to end up with nice meat, but the skin, well, it's much thicker, and even roasted carefully, it's thick and hard to chew. At 9 months, that's a bit past my ideal window for roasting to have tasty skin.
Now, stocking - that's where they would both shine in - after processing, chunk them up into parts (leaving the skin on, and you can also put in the neck, gizzards, and heart, though the liver isn't the best for stock), put it all in a big stock pot with some veggies like onions, carrots and celery. Throw some whole peppercorns in. Let them simmer, covered, on a low heat for a few hours. Take them out, shred the meat all off, and them put the bones and stuff back in, add more water and simmer for a couple more hours. Strain through a colander to get the big pieces, then through a cheesecloth for little bits, into pitchers or whatnot (I use a couple gallon pitchers). Stick in the fridge and let them sit for a few hours or the next day. Skim off the hardened fat from the top, put the fat in a tupperware dish in the fridge, and then portion the stock into freezeable containers or baggies for cooking potions (one cup or two). Use the meat for whatever you want.
I like to keep out a part of the fresh stock for chicken noodle soup or chicken and dumplings :) I use the fat for flavoring potatoes instead of using butter.