I've dry brined for several years and the birds (Butterball & Jenny-O) always come out tasty and tender. Have done this when using both the rotisserie and pellet grill. Really never found any need to inject turkeys, or any other meat.
I bought an organic turkey and injected this year. I had done some chickens this way earlier. They were great, so I figured I'd give this a shot. I used some turkey stock, butter, and a rub mixed together.