Body harness vs. Neck collar?

Yes, it's fine. A collar/leash can choke a dogs if they pull and you stop it chokes them. A harness is much better because it makes them stop without causing stress to the neck. Then again it is a puppy, puppies do that until you train them. You should leash train your puppy then you won't have those problems anymore. If he pulls just stands and turn around he stars acting up show him you won;'t move unless he walks with you. Then you shouldn't have any problems. But a harness is a whole lot safer and better in my opinion.