Count me in as against the half shield. The reduction in vision is more mental than acutual, I use to have a study that backed that up, but have lost it.
Also, there is this.....http://bjsm.bmj.com/content/36/1/27.abstract?sid=374eeb4f-6553-46eb-9e3e-6427e15b6a6a
Seems enough reason to me to mandate the full cage, especially in young developing brains.
I take care of eyes for a living, ive seen the ugly of some of these things, and although I do respect a person's free will, i think organizationally, the NCAA, USHL, etc..has a liability to take care of these players, and ultimately that is why you wont see it change.