while I personally detest things on my neck (ie, my dog tags), if it's for you, more power to you. I think that NightHiker has a good compromise of good and bad. Ranger Rick's is a good idea to peruse too, but take what he says with a grain of salt, he seems to have great ideas interspersed with gizmo's.

I think the regular "dog tag" chains break with enough force. The only down side I have to them is mine keeps snagging on chest hair. It's really annoying!

paracord is a good idea, as is using a wire saw.