I just think it's advantageous to stick with something that's comfortable. I always lead with the hands when I push towards the target and the hold the finish until the ball reaches the hole.

I've tried rocking the shoulder but I find it makes me swing "out to in" slightly. Incidently, when I put my shoulders do rock, it's impossible for them not to, but I always feel the first movement is from the hands rather than an upper body movement.