What would I have to change re: time and temp?
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Sure. I would argue that, while roast chicken does really well at a higher heat (425), pieces should be cooked at a lower temp (375) simply because they have less mass and would tend to dry out quicker than a whole chicken. And they definitely won't take as long as a whole chicken, although I can't say off the top of my head how long. Ideally, your chicken pieces are skin-on. Otherwise, they will probably end up dry.
I would say, rub down the chicken with salt and pepper, and maybe a little olive oil or butter (I normally don't do that for whole chicken, but for chicken pieces it's insurance against dry meat). Roast at 375 for 30 minutes, skin side up. Check the temperature to see if they're done (165 degrees is officially "done" but you'll want to pull it out a little earlier because the internal temp will rise slightly as the meat rests), and proceed accordingly.
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Mostly I agree with petitbleu on this, except that I would stay with the higher heat (425F) rather than the lower one. Just be sure to baste frequently with pan juices and maybe some white wine that you have on the side. The "official" 165F for doneness is simply way too high. That's a bureaucrat's idea of food safety. What you are after is a crispy skin (which you won't get at lower heat) but a moist interior. The rub down method is exactly what I would do also.
You *can* roast a cut-up chicken but you'd be better off with a whole bird if you have a choice. Among other troubles perfecting roasted pieces is getting the skin crispy at the same time the interior comes up to temp. Huge breasts have the advantage here (no jokes please) because they give the skin more time to cook.
As for Keller's birds, he has / had two approaches: his simple truss-it-and-throw-it in-the-oven-I'm-with-friends method and his upscale, brined version. Both are excellent. He roasts in a very hot oven, 450-475F, I have better results at 450. Different size birds will cook at different rates and require different temperatures. If you're going with pieces, you'll probably want to give the dark meat a head start.
As for the dryness issue, there are only two things that are under your control -- brining and internal temperature. Let me assure you, you can cook to the full USDA specs and have a perfectly tender and juicy bird. Pull the breasts between 155 and 160 (depends on oven temp) and dark meat 10F higher. The temp should continue to rise to 165 / 175.
Okay, Pierino is screaming about now. First let me say that, not only could I get in hot water if I advised otherwise, that is how I cook (as does Keller). Sick people are bad for business. On the other hand, depending upon personal preference, you *can* cook to a lower temperature and remain safe *if* you have an accurate thermometer and understand the time factor.
Food is considered pasteurized if it remains at 160F for 10 seconds. The extra 5 degrees is a safety factor for chicken which has a very high incidence of salmonella contamination (in my kitchen we refer to raw chicken juice as salmonella juice to remind ourselves of the danger). A minute and a half at 150F will render food safe but it takes over 12 minutes at 140F and over two hours at 130F. Does it take more than one and a half minutes for a bird to go from 150 to 160? Yes. But are you sure you probed the coolest part of the entire bird? Do you feel lucky?
Pierino is not screaming at all because we liked ChefOno's answer. In fact our favorite chefs are Keller, David Chang and ChefOno. If you ask any of the chefs I know what their favorite meal to cook at home is, the answer will almost always be a roast chicken. Now for salmonella you could go for that spicey tuna roll, caught in south Asia and processed in California and shipped to New York.