I'm fully aware of what a spatchcock chicken is. My question was directed to the OP.
To the OP, chicken is very lean and takes on smoke rather quickly. With that said there really isn't any benefit to cooking it low and slow. From my experiences indirect high heat works best. You'll get juicy meat with crispy skin. Some people like to brine, inject, or marinate their chicken for additional flavor or juiciness. It all works. If you marinate your chicken and cook it with high heat just remember you run the risk of the sugars in the marinate burning. Some folks compare over-smoked poultry to the taste of licking an ashtray. I've never licked an ashtray so I cannot agree or disagree, but I do know over-smoked chicken tastes rancid.
325* is about the lowest temp when doing poultry. I only brine chicken breasts, and brine them in pickle juice. It works for me. Others use recipes like POPs brine, and their chicken looks and sounds terrific. Keep asking questions and we'll get you the chicken you want.
Chris