I think it depends on what line you go into. My dad's an opthalmologist, so as much as it would seem that he doesn't need to take work home with him, sometimes it does get to him emotionally. Apart from the massive amount of paper work he has to do, he gets some cases that are sad, for example, car crash victims, and there have been instances when people have gone to him concerning eye pain and he's ended up finding they had a brain tumour.
I don't think distancing yourself emotionally hinders your work as a doctor either. Personally, I think it may even make you a better doctor, not letting your own personal emotions get in the way of what you do. Doctor's have to be impartial and open minded, not everything they say goes lol. And if you were to get hung up on every patient, then I don't think one could survive in such a profession.. having said that being completely void of emotion isn't the way to go either. Having emotions for your patients will help keep the passion in the job, which so many people lose after ten years.
I think no matter what sort of doctor you are, it in a way will take over your life, but it also depends on the type of person you are. It's not as if my dad has no free time, he plays golf A LOT, and he works privately and for the NHS. Meh, I guess it depends...although today he came home at half nine from the private practice.