I feel the whole behind-the-neck-presses debate is very overhyped. I, for one, perform my presses to the front of the body. But at saying that, i have performed them behind the neck, and they did not bother me at all. I feel it comes down to how flexible your shoulders are. If you have tight shoulders, that position would be very uncomfortable, but if you have relatively flexible shoulder/joints, they probably won't hurt you.
At saying that though, i still would recommend performing them in front of the body.