Intriguting discussion. Because I tend to prefer bondage and we don't get very heavily into D/s, I don't have much experience to draw from, but I do have one thought:

I think you can do psychological without physical, but I think it's harder to do physical without psychological. It seems to me that it would be hard to physically dominate someone without capturing their mind along the way. But you can mess with somebody's mind without ever laying a finger on the person.