I've done it both ways. Honestly, brine is a pita. Just inject with cajun butter or your favorite homemade garlic butter or whatever, let it rest for a few hours so the mixture soaks into the meat, rub with olive oil, and smoke it.
I don't think a brine does anything that an injector and some good flavorful mixture can't do. Your turkey shouldn't get dry by just smoking it. The skin holds in much of the moisture and the injector puts more in.
Serious eats thinks a dry brine is the way to go.. in other words, no moisture other than what is present in the bird already. In the end, try it with or without brine and see what you think.