I don't have a link, but it's getting more and more common to see those whistles embedded in a sternum strap buckle. Only problem I see with them is that if you take your pack off and wander around the meadow with your camera or whatever, then there goes your whistle.

Maybe I'm a little over cautious, but I like wearing a whistle, a compass, a p-38 can opener, a little key chain type LED squeeze light, and an ID tag around my neck.

I actually find the compass and the little light useful around town. I pulled out of a parking garage the other day. The exit was on a totally different street than the one I entered from. I saw no recognizable landmark. I pulled out my compass. I immediately knew I was headed south and therefore needed to turn left. I drove a block or so, saw a street I recognized, and was on my way. Handy.

HJ