I use a chesty. So it's right in front of me. Yes, there is a weight and size disadvantage but it is not in my pack. I can bust it out quickly, get the shots, through it back in and go. I am surprised by how little having it on my chest bothers me.
I have to agree that the NEX camera's are great and you should get plenty of great shots with one. I may purchase one in the future, though the wife will probably kill me. I don't have any super crazy glass. A decent Telephoto and a wide angle that came with the camera kit.