I am wondering about your use of metal hook, does it not leave scrap marks on the camera body?
I would also worry about the safety pin accidentally depressing, and unhooking for a disaster.
No scrap marks so far, but then again; the hooks are only used for carrying the camera under coat in extreme cold weather. When taking pics, I just unhook camera and leave the strap hanging around my neck. Works fine. Besides, the hooks are very light and tiny.
Safety pin is actually quite firm and btw. I always hook with safety pin pointing towards the camera body, i.e. opposite of what the picture shows... sigh.
Sorry about the poor image quality - bad light, handheld, tiny D40 at work.
Should things however go horrible wrong one day, I'll post story and images here: http://nikonrumors.com/forum/topic.php?id=5382